Signing off

Signing off

[Bob Rosebrugh]

Dear Colleagues,

From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.

Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.

It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.

Best wishes to everyone. I am hoping to see many of you in the not distant future,
Bob Rosebrugh



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Re: Signing off

[Keith Harbaugh]

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The greatest possible thanks and appreciation for your services to the
categorical community.

On Thu, Oct 26, 2023, 15:53 Bob Rosebrugh <rrosebru@mta.ca> wrote:

>
> Dear Colleagues,
>
> From March 1990 until recently it was my privilege to moderate the
> categories mailing list. For a couple of years it has been my intention to
> pass the list to a new moderator, but I was too slow to act. Changes to IT
> service at my former employer, Mount Allison University, abruptly made it
> impossible for me to continue running the list.
>
> Those changes were unexpected for me, but I have been away from the campus
> for over three years and was not aware. The IT staff at Mount Allison have
> always been very supportive of the list and I thank them for their more
> than three decades of generous assistance.
>
> It is a reassuring pleasure to know that the list is now in the capable
> hands of JS Lemay who kindly accepted the invitation to revive it. I am
> very grateful. Moreover, there is no one better suited to the role and our
> community is fortunate to have him moderating. I am also very happy that
> the new home of the list is Macquarie.
>
> Best wishes to everyone. I am hoping to see many of you in the not distant
> future,
> Bob Rosebrugh
>
>
>
> ----------
>
> You're receiving this message because you're a member of the Categories
> mailing list group from Macquarie University.
>
> Leave group:
>
> https://protect-au.mimecast.com/s/O0b5CWLVn6i3RkOrH6g1rj?domain=outlook.office365.com
>

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Re: Signing off

[Jirí Adámek]

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Dear Bob,

The fact that you created the mailing list and moderated it for three 
decades was a wonderful service to the categorical community! 
It provided us with a much needed synergy, and helped the distribution
of important news about our field. I remember a couple of instances when
your role was not entirely easy, and I always felt your decisions in such 
situations were very well made.

Thank you so much for all your effort!!!

Jiri


On Thu, 26 Oct 2023, Bob Rosebrugh wrote:

>
> Dear Colleagues,
>
> From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.
>
> Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.
>
> It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.
>
> Best wishes to everyone. I am hoping to see many of you in the not distant future,
> Bob Rosebrugh
>
>
>
> ----------
>
> You're receiving this message because you're a member of the Categories mailing list group from Macquarie University.
>
> Leave group:
> https://protect-au.mimecast.com/s/1e1iCBNqgBCqpnlmfzFzj1?domain=outlook.office365.com
>

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Re: Signing off

[Robin Cockett]

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Hi Bob,

Thank you for your amazing service to the community ... which was happening for as long as I can remember!)

... and you have handed it off so smoothly and gracefully!

Doubly amazing!

-robin
________________________________
From: Bob Rosebrugh <rrosebru@mta.ca>
Sent: Thursday, October 26, 2023 8:14 AM
To: categories@mq.edu.au <categories@mq.edu.au>
Subject: Signing off

[△EXTERNAL]



Dear Colleagues,

From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.

Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.

It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.

Best wishes to everyone. I am hoping to see many of you in the not distant future,
Bob Rosebrugh



----------

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Re: [EXT] Re: Signing off

[Bob Coecke]

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Bob, very few can be bothered to make these sort of efforts.  These commitments are an essential component of community building, caring about your peers, and caring about academic offspring, the kids.  Besides your academic work, which is very important, these community building efforts you did is what shapes the future of a community.  Your commitment kept the category community present, in not so easy times.  Thanks Bob!
________________________________
From: Jir? Ad?mek <j.adamek@tu-bs.de>
Sent: 26 October 2023 22:16
To: Bob Rosebrugh <rrosebru@mta.ca>
Cc: categories@mq.edu.au <categories@mq.edu.au>
Subject: [EXT] Re: Signing off


CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.


Dear Bob,

The fact that you created the mailing list and moderated it for three
decades was a wonderful service to the categorical community!
It provided us with a much needed synergy, and helped the distribution
of important news about our field. I remember a couple of instances when
your role was not entirely easy, and I always felt your decisions in such
situations were very well made.

Thank you so much for all your effort!!!

Jiri


On Thu, 26 Oct 2023, Bob Rosebrugh wrote:

>
> Dear Colleagues,
>
> From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.
>
> Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.
>
> It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.
>
> Best wishes to everyone. I am hoping to see many of you in the not distant future,
> Bob Rosebrugh
>
>
>
> ----------
>
> You're receiving this message because you're a member of the Categories mailing list group from Macquarie University.
>
> Leave group:
> https://protect-au.mimecast.com/s/OASZCvl1g2S1pnqBSQ4lzw?domain=outlook.office365.com<https://protect-au.mimecast.com/s/OASZCvl1g2S1pnqBSQ4lzw?domain=outlook.office365.com>
>

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Re: Signing off

[Steve Awodey]

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Dear Bob,
Many thanks for your years of service!
Best wishes,
Steve 

> On Oct 26, 2023, at 15:52, Bob Rosebrugh <rrosebru@mta.ca> wrote:
> 
> 
> Dear Colleagues,
> 
> From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.
> 
> Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.
> 
> It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.
> 
> Best wishes to everyone. I am hoping to see many of you in the not distant future,
> Bob Rosebrugh
> 
> 
> 
> ----------
> 
> You're receiving this message because you're a member of the Categories mailing list group from Macquarie University.
> 
> Leave group:
> https://protect-au.mimecast.com/s/k8poCwV1jpS6J5YWIVTAc0?domain=outlook.office365.com

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Re: Signing off

[Valeria de Paiva]

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Dear Bob,
I want to join the chorus of people who are writing to say "THANK YOU" for
all these years moderating the list.
But I also want to pay tribute to your vision all those many years ago in
creating the list, helping to set up TAC, and, especially, managing it for
so many years!
Many thanks,
Valeria

On Thu, Oct 26, 2023 at 12:52 PM Bob Rosebrugh <rrosebru@mta.ca> wrote:

>
> Dear Colleagues,
>
> From March 1990 until recently it was my privilege to moderate the
> categories mailing list. For a couple of years it has been my intention to
> pass the list to a new moderator, but I was too slow to act. Changes to IT
> service at my former employer, Mount Allison University, abruptly made it
> impossible for me to continue running the list.
>
> Those changes were unexpected for me, but I have been away from the campus
> for over three years and was not aware. The IT staff at Mount Allison have
> always been very supportive of the list and I thank them for their more
> than three decades of generous assistance.
>
> It is a reassuring pleasure to know that the list is now in the capable
> hands of JS Lemay who kindly accepted the invitation to revive it. I am
> very grateful. Moreover, there is no one better suited to the role and our
> community is fortunate to have him moderating. I am also very happy that
> the new home of the list is Macquarie.
>
> Best wishes to everyone. I am hoping to see many of you in the not distant
> future,
> Bob Rosebrugh
>
>
>
> ----------
>
> You're receiving this message because you're a member of the Categories
> mailing list group from Macquarie University.
>
> Leave group:
>
> https://protect-au.mimecast.com/s/6kolCL7Eg9fqyqPgTBXYpK?domain=outlook.office365.com
>

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Re: Signing off

[Alexander Kurz]

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Thanks, Bob. I have been on the list since my days as a PhD student in the 1990s. At the time there was not too much happening online. The categories mailing list had a profound influence on my career and feels a bit like home ... thank you so much.

> On Oct 26, 2023, at 3:42 PM, Steve Awodey <awodey@cmu.edu> wrote:
> 
> Dear Bob,
> Many thanks for your years of service!
> Best wishes,
> Steve 
> 
> > On Oct 26, 2023, at 15:52, Bob Rosebrugh <rrosebru@mta.ca> wrote:
> > 
> > 
> > Dear Colleagues,
> > 
> > From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.
> > 
> > Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.
> > 
> > It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.
> > 
> > Best wishes to everyone. I am hoping to see many of you in the not distant future,
> > Bob Rosebrugh
> > 
> > 
> > 
> > ----------
> > 
> > You're receiving this message because you're a member of the Categories mailing list group from Macquarie University.
> > 
> > Leave group:
> > https://protect-au.mimecast.com/s/EB8zCyoj8PuDqB5kCZd_yU?domain=outlook.office365.com


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Re: Signing off

[johnm]

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Dear Bob,

Your service over these many years has been greatly appreciated. It has
promoted many valuable connections for me and was of the utmost help to me
when holding many CT and FMCS conferences in Vancouver. I am glad to see
that this valuable forum for category theory has been transferred so
smoothly and will hopefully continue for many years to come.

Regards,

Lauchie MacDonald


>> On Oct 26, 2023, at 15:52, Bob Rosebrugh <rrosebru@mta.ca> wrote:
>>
>> 
>> Dear Colleagues,
>>
>> From March 1990 until recently it was my privilege to moderate the
>> categories mailing list. For a couple of years it has been my intention
>> to pass the list to a new moderator, but I was too slow to act. Changes
>> to IT service at my former employer, Mount Allison University, abruptly
>> made it impossible for me to continue running the list.
>>
>> Those changes were unexpected for me, but I have been away from the
>> campus for over three years and was not aware. The IT staff at Mount
>> Allison have always been very supportive of the list and I thank them
>> for their more than three decades of generous assistance.
>>
>> It is a reassuring pleasure to know that the list is now in the capable
>> hands of JS Lemay who kindly accepted the invitation to revive it. I am
>> very grateful. Moreover, there is no one better suited to the role and
>> our community is fortunate to have him moderating. I am also very happy
>> that the new home of the list is Macquarie.
>>
>> Best wishes to everyone. I am hoping to see many of you in the not
>> distant future, Bob Rosebrugh
>>
>>
>>
>> ----------
>>
>> You're receiving this message because you're a member of the Categories
>> mailing list group from Macquarie University.
>>
>> Leave group:
>> https://protect-au.mimecast.com/s/k8poCwV1jpS6J5YWIVTAc0?domain=outlook.office365.com<https://protect-au.mimecast.com/s/qs6ZCzvkmpfD6MQNsX4AO_?domain=outlook.office365.com>
>


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Re: Signing off

[Ross Street]

Dear Bob

Far away in time and distance from most of your readers Max Kelly, in Australia,
decided to make a mailing list of category theorists he knew from conferences;
I contributed some more people. The list was typed on a golfball IBM typewriter.
When we had a preprint or two (and once, a ``Christmas Letter''), we would photocopy
the list onto sheets of address labels, put the preprints in envelopes, and mail them
using the reliable postal system of the 1970s.

Once we sent the list itself around too. Mike Barr wrote or said to Max: ``What am I supposed
to do with this!'' Max explained what we did. However, by then, word processors were
around and Mike wanted an electronic version. We moved to that. The first word processor
our Macquarie Mathematics Department secretaries used was called ``OK editor'', not great.
Of course then in came email and work stations and personal computers and TeX, . . . ; you
know the story.

In 1990, you stepped in with prescient creations: a social medium for category theory
and one of the very first electronic mathematics journals.
What a debt our subject owes you!! You dedicated so much to running both magnificently.
So easy to say ``thank you'', and I do. However, with all the thanks flowing in, our joint
appreciation should be clear.

It is a hard act to follow. Luckily, JS has stepped forward and already managed to have
a replacement system up and running. I have full confidence that he will run it well, he
is so bright and energetic. Moreover, I told the little story in the first paragraph to express
my feeling of some satisfaction that the system has come to this far, distant land.

Surely now Bob, you will have a bit more time for research and other things.
You deserve it.

With best regards,
Ross

> On 27 Oct 2023, at 1:14 am, Bob Rosebrugh <rrosebru@mta.ca> wrote:
>
>
> Dear Colleagues,
>
> From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.
>
> Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.
>
> It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.
>
> Best wishes to everyone. I am hoping to see many of you in the not distant future,
> Bob Rosebrugh
>



----------

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Leave group:
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Re: Signing off

[Vaughan Pratt]

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Ross and I were two of the 14 students who took Honours Pure Maths at the
University of Sydney in 1965.  My mother was Marjorie Pratt, a champion
diver in the 1930's, and as luck would have it, Ross's wife is also
Marjorie.

G'day, mate.

Vaughan

On Thu, Oct 26, 2023 at 9:51 PM Ross Street <ross.street@mq.edu.au> wrote:

> Dear Bob
>
> Far away in time and distance from most of your readers Max Kelly, in
> Australia,
> decided to make a mailing list of category theorists he knew from
> conferences;
> I contributed some more people. The list was typed on a golfball IBM
> typewriter.
> When we had a preprint or two (and once, a ``Christmas Letter''), we would
> photocopy
> the list onto sheets of address labels, put the preprints in envelopes,
> and mail them
> using the reliable postal system of the 1970s.
>
> Once we sent the list itself around too. Mike Barr wrote or said to Max:
> ``What am I supposed
> to do with this!'' Max explained what we did. However, by then, word
> processors were
> around and Mike wanted an electronic version. We moved to that. The first
> word processor
> our Macquarie Mathematics Department secretaries used was called ``OK
> editor'', not great.
> Of course then in came email and work stations and personal computers and
> TeX, . . . ; you
> know the story.
>
> In 1990, you stepped in with prescient creations: a social medium for
> category theory
> and one of the very first electronic mathematics journals.
> What a debt our subject owes you!! You dedicated so much to running both
> magnificently.
> So easy to say ``thank you'', and I do. However, with all the thanks
> flowing in, our joint
> appreciation should be clear.
>
> It is a hard act to follow. Luckily, JS has stepped forward and already
> managed to have
> a replacement system up and running. I have full confidence that he will
> run it well, he
> is so bright and energetic. Moreover, I told the little story in the first
> paragraph to express
> my feeling of some satisfaction that the system has come to this far,
> distant land.
>
> Surely now Bob, you will have a bit more time for research and other
> things.
> You deserve it.
>
> With best regards,
> Ross
>
> > On 27 Oct 2023, at 1:14 am, Bob Rosebrugh <rrosebru@mta.ca> wrote:
> >
> >
> > Dear Colleagues,
> >
> > From March 1990 until recently it was my privilege to moderate the
> categories mailing list. For a couple of years it has been my intention to
> pass the list to a new moderator, but I was too slow to act. Changes to IT
> service at my former employer, Mount Allison University, abruptly made it
> impossible for me to continue running the list.
> >
> > Those changes were unexpected for me, but I have been away from the
> campus for over three years and was not aware. The IT staff at Mount
> Allison have always been very supportive of the list and I thank them for
> their more than three decades of generous assistance.
> >
> > It is a reassuring pleasure to know that the list is now in the capable
> hands of JS Lemay who kindly accepted the invitation to revive it. I am
> very grateful. Moreover, there is no one better suited to the role and our
> community is fortunate to have him moderating. I am also very happy that
> the new home of the list is Macquarie.
> >
> > Best wishes to everyone. I am hoping to see many of you in the not
> distant future,
> > Bob Rosebrugh
> >
>
>
>
> ----------
>
> You're receiving this message because you're a member of the Categories
> mailing list group from Macquarie University.
>
> Leave group:
>
> https://protect-au.mimecast.com/s/BBzTC1WLjwsg3OR4TLQkkb?domain=outlook.office365.com
>

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Re: Signing off

[Patrik Eklund]

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Dear all,

Thank you for mailing, throughout decades, as it has helped create new 
things and invite younger researchers, at the same time it preserves 
community and maintains a forum.

I've learned a lot, and I am grateful for that.

---

Yes, looking back, we have good memories, and we know we did the right 
things. Many things we wouldn't have done differently.

Are we looking forward? What's in for CT in 50-100 years to come?

I'm less than epsilon in the universe on CT knowledge but allow me to 
write this.

---

I wrote recently to Michael Barr privately as I had found a mail 
exchange from 2015.

On 2015-01-29 02:59, Michael Barr wrote:
I wonder what kind of science outside of string theory would find CT 
useful.

I wrote some, and related to what I have posted sometimes at CT (and 
FoM) on the need to use CT in understanding syntax within the 
foundations of logic.

---
---
---

Here's what I (somewhat shortened) wrote to Michael:

I have come back to that "outside of string theory". For decades I was 
flabbergasted about Gödel's fame given his 1931 paper. He is basically 
very shallow on formalising what formulas and provable formulas actually 
are. Once he has sets for these, no matter what they are, he sees 
formulas in there as sequences of symbols, and proofs as sequences of 
sequences of symbols. In his footnote 9 he says he works with an 
"isomorphic image" of Principia Mathematica. It could and should be an 
adjunction if he would have tried something out.

Anyway, in Gödel's use of the power type, he essentially works with 
terms over sets rather than sets of terms, i.e.. he leans on the TP 
composition rather than the PT composition. So basically he doesn't 
realize that his substitutions cannot compose. His efforts on 
substitution is in his steps 30 and 31 in his 1-46 steps before he 
"proves" his incompleteness results.

So basically Gödel proves incompleteness of systems that actually do not 
exist anywhere. Saying that whatever system P we have, formulas must be 
nothing but sequences of symbols (Peano 1889), and proofs are sequences 
of such sequences, is absurd.

---

On 2015-01-29 02:59, Michael Barr wrote: I wonder what kind of science 
outside of string theory would find CT useful.

Today I write: I wonder why CT never looked into being useful more 
generally within fuondations, and not just marginally curious about its 
own foundations.

Gödel's meta language is "logical arithmetic" where his "numbers" and 
recursion reside, and he uses that to drag sequences of sequences of 
symbols into the mud. So I wonder why CT never looked into using 
categorical arithmetic as meta to enrich Hilbert's program. Gödel's 1931 
paper is seen as having crashed everything about Hilbert's program, and 
he did it by dragging sequences of sequences of symbols into the mud.

---

The Foundations of Mathematics side never seriously looked into CT, and 
CT never seriously looked into FoM.

I always wondered why.

---
---
---

That was indeed my mail to Michael a few days ago.

To repeat: Are we looking forward? What's in for CT in 50-100 years to 
come?

Some 50 years ago Bernays and Gödel exchanged letters on category 
theory. They had heard something about someone being in Poland, but that 
was basically it.

Today, is there any exchange at all between CT and FoM (not the mailing 
lists!)?

---

Thank you Bob Rosebrugh for everything you've done, and thank you JS 
Lemay in advance for everything you will do.

Best,

Patrik



On 2023-10-26 17:14, Bob Rosebrugh wrote:
> Dear Colleagues,
> 
> From March 1990 until recently it was my privilege to moderate the
> categories mailing list. For a couple of years it has been my
> intention to pass the list to a new moderator, but I was too slow to
> act. Changes to IT service at my former employer, Mount Allison
> University, abruptly made it impossible for me to continue running the
> list.
> 
> Those changes were unexpected for me, but I have been away from the
> campus for over three years and was not aware. The IT staff at Mount
> Allison have always been very supportive of the list and I thank them
> for their more than three decades of generous assistance.
> 
> It is a reassuring pleasure to know that the list is now in the
> capable hands of JS Lemay who kindly accepted the invitation to revive
> it. I am very grateful. Moreover, there is no one better suited to the
> role and our community is fortunate to have him moderating. I am also
> very happy that the new home of the list is Macquarie.
> 
> Best wishes to everyone. I am hoping to see many of you in the not
> distant future,
> Bob Rosebrugh
> 
> 
> 
> ----------
> 
> You're receiving this message because you're a member of the
> Categories mailing list group from Macquarie University.
> 
> Leave group:
> https://protect-au.mimecast.com/s/F_r_C4QO8xSPgRRASOwJwn?domain=outlook.office365.com

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Re: Signing off

[Vaughan Pratt]

[-- Attachment #1: Type: text/plain, Size: 2796 bytes --]

 Bob,

I really appreciate all the effort you've put into keeping this list
running for so long, as well as keeping its tone light and bright.

It's interesting to compare it with the Foundations of Mathematics (FOM)
list, which early on tended to be dominated by Harvey Friedman, who started
it in 1997.  Harvey was later joined by Steve Simpson, who rather
dogmatically did not suffer category theory gladly, to the point of driving
Sol Feferman to shout Basta! before quitting the list.

Shades of the similarly dogmatic Universal Algebra and Category Theory
conference co-organized by Ralph McKenzie and Saunders Mac Lane and held at
MSRI, Berkeley in July 1993.  The opening welcome was given by MSRI
director Bill Thurston, who in mid-welcome admitted that the opposite of a
morphism made him feel ill!  An inaudible gasp from fully half the audience
echoed round the room.

When Martin Davis took over FOM's administration, true to form he kept it
sharply focused, arguably a little too much sometimes.  Eventually Martin
passed his job on to Sam Buss, who has been running it more in your more
forgiving style, with much the same view as you as to when it was time to
bring a thread to an end.

May the reigning dogmas and cats live long, and maybe even prosper!

Cheers from Up Over,
Vaughan Pratt

On Thu, Oct 26, 2023 at 12:52 PM Bob Rosebrugh <rrosebru@mta.ca> wrote:

>
> Dear Colleagues,
>
> From March 1990 until recently it was my privilege to moderate the
> categories mailing list. For a couple of years it has been my intention to
> pass the list to a new moderator, but I was too slow to act. Changes to IT
> service at my former employer, Mount Allison University, abruptly made it
> impossible for me to continue running the list.
>
> Those changes were unexpected for me, but I have been away from the campus
> for over three years and was not aware. The IT staff at Mount Allison have
> always been very supportive of the list and I thank them for their more
> than three decades of generous assistance.
>
> It is a reassuring pleasure to know that the list is now in the capable
> hands of JS Lemay who kindly accepted the invitation to revive it. I am
> very grateful. Moreover, there is no one better suited to the role and our
> community is fortunate to have him moderating. I am also very happy that
> the new home of the list is Macquarie.
>
> Best wishes to everyone. I am hoping to see many of you in the not distant
> future,
> Bob Rosebrugh
>
>
>
> ----------
>
> You're receiving this message because you're a member of the Categories
> mailing list group from Macquarie University.
>
> Leave group:
>
> https://protect-au.mimecast.com/s/QaT4COMK7YcYnEYLIEwTL-?domain=outlook.office365.com
>

[-- Attachment #2: Type: text/html, Size: 3954 bytes --]

Re: Signing off

[Manuela Sobral]

[-- Attachment #1: Type: text/plain, Size: 1606 bytes --]

Dear Bob,

Let me join those that are saying "thank you" for your great services

to the categorical community. Many more benefited from them and

are also, surely, much grateful.

Best regards and wishes,

Manuela

On 26/10/2023 15:14, Bob Rosebrugh wrote:
> Dear Colleagues,
>
>  From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.
>
> Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.
>
> It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.
>
> Best wishes to everyone. I am hoping to see many of you in the not distant future,
> Bob Rosebrugh
>
>
>
> ----------
>
> You're receiving this message because you're a member of the Categories mailing list group from Macquarie University.
>
> Leave group:
> https://protect-au.mimecast.com/s/JBYaC91W8rCnQ977ioRzAq?domain=outlook.office365.com

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Re: Signing off

[Clemens Berger]

[-- Attachment #1: Type: text/plain, Size: 1863 bytes --]

Dear Bob,

   many, many thanks for your visionary adventure, more than 30 years 
ago, into the digital world of communication. This was not only a way of 
connecting people with same interests, but also the installment of a 
solid platform for the promotion of category theory and the exchange of 
exciting new ideas.

   I hope to see you soon (at CT 2024 or in Nice ?),

All the best,
                   Clemens.

Le 2023-10-26 16:14, Bob Rosebrugh a écrit :
> Dear Colleagues,
> 
> From March 1990 until recently it was my privilege to moderate the
> categories mailing list. For a couple of years it has been my
> intention to pass the list to a new moderator, but I was too slow to
> act. Changes to IT service at my former employer, Mount Allison
> University, abruptly made it impossible for me to continue running the
> list.
> 
> Those changes were unexpected for me, but I have been away from the
> campus for over three years and was not aware. The IT staff at Mount
> Allison have always been very supportive of the list and I thank them
> for their more than three decades of generous assistance.
> 
> It is a reassuring pleasure to know that the list is now in the
> capable hands of JS Lemay who kindly accepted the invitation to revive
> it. I am very grateful. Moreover, there is no one better suited to the
> role and our community is fortunate to have him moderating. I am also
> very happy that the new home of the list is Macquarie.
> 
> Best wishes to everyone. I am hoping to see many of you in the not
> distant future,
> Bob Rosebrugh
> 
> 
> 
> ----------
> 
> You're receiving this message because you're a member of the
> Categories mailing list group from Macquarie University.
> 
> Leave group:
> https://protect-au.mimecast.com/s/CJo2Cp81gYCkmgWySP4Mx8?domain=outlook.office365.com

[-- Attachment #2: Type: text/html, Size: 2370 bytes --]

Re: Signing off

[Robert Dawson]

[-- Attachment #1: Type: text/plain, Size: 1526 bytes --]

Thanks for everything, Bob! The CT list will be a monument "more 
enduring than brass" to your time at the helm.

Cheers,

Robert Dawson

On 10/26/2023 11:14 AM, Bob Rosebrugh wrote:
> Dear Colleagues,
>
> >From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.
>
> Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.
>
> It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.
>
> Best wishes to everyone. I am hoping to see many of you in the not distant future,
> Bob Rosebrugh
>
>
>
> ----------
>
> You're receiving this message because you're a member of the Categories mailing list group from Macquarie University.
>
> Leave group:
> https://protect-au.mimecast.com/s/G_5eCoV1Y2S9E38ZH1KFSG?domain=outlook.office365.com

[-- Attachment #2: Type: text/html, Size: 1914 bytes --]

Re: Signing off

[Robert Pare]

[-- Attachment #1: Type: text/plain, Size: 1774 bytes --]

Bob,

What can I add to what's already been said? Only that I
appreciate everything you've done for category theory in
general and "Atlantic category theory" in particular:
Categories, TAC and @CAT.

Cheers,

Bob
________________________________
From: Bob Rosebrugh <rrosebru@mta.ca>
Sent: October 26, 2023 11:14 AM
To: categories@mq.edu.au <categories@mq.edu.au>
Subject: Signing off

CAUTION: The Sender of this email is not from within Dalhousie.

Dear Colleagues,

From March 1990 until recently it was my privilege to moderate the categories mailing list. For a couple of years it has been my intention to pass the list to a new moderator, but I was too slow to act. Changes to IT service at my former employer, Mount Allison University, abruptly made it impossible for me to continue running the list.

Those changes were unexpected for me, but I have been away from the campus for over three years and was not aware. The IT staff at Mount Allison have always been very supportive of the list and I thank them for their more than three decades of generous assistance.

It is a reassuring pleasure to know that the list is now in the capable hands of JS Lemay who kindly accepted the invitation to revive it. I am very grateful. Moreover, there is no one better suited to the role and our community is fortunate to have him moderating. I am also very happy that the new home of the list is Macquarie.

Best wishes to everyone. I am hoping to see many of you in the not distant future,
Bob Rosebrugh



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Re: Signing off

[George Janelidze]

[-- Attachment #1: Type: text/plain, Size: 3774 bytes --]

Dear Bob,

Let me join Lauchie and all others who greatly appreciated, saying it loudly or not, what your so big, intelligent, and kind work did to our community. Instead of "we will miss you" I want to say "see you" because I hope we will communicate with you and see you, at least on CT conferences, as before.

Thank you so much, and
Very best regards to you,
George

From: johnm@math.ubc.ca<mailto:johnm@math.ubc.ca>
Sent: Friday, October 27, 2023 6:30 AM
To: Bob Rosebrugh<mailto:rrosebru@mta.ca>
Cc: categories@mq.edu.au<mailto:categories@mq.edu.au> ; johnm@math.ubc.ca<mailto:johnm@math.ubc.ca>
Subject: Re: Signing off


Dear Bob,

Your service over these many years has been greatly appreciated. It has
promoted many valuable connections for me and was of the utmost help to me
when holding many CT and FMCS conferences in Vancouver. I am glad to see
that this valuable forum for category theory has been transferred so
smoothly and will hopefully continue for many years to come.

Regards,

Lauchie MacDonald


>> On Oct 26, 2023, at 15:52, Bob Rosebrugh <rrosebru@mta.ca<mailto:rrosebru@mta.ca>> wrote:
>>
>> 
>> Dear Colleagues,
>>
>> From March 1990 until recently it was my privilege to moderate the
>> categories mailing list. For a couple of years it has been my intention
>> to pass the list to a new moderator, but I was too slow to act. Changes
>> to IT service at my former employer, Mount Allison University, abruptly
>> made it impossible for me to continue running the list.
>>
>> Those changes were unexpected for me, but I have been away from the
>> campus for over three years and was not aware. The IT staff at Mount
>> Allison have always been very supportive of the list and I thank them
>> for their more than three decades of generous assistance.
>>
>> It is a reassuring pleasure to know that the list is now in the capable
>> hands of JS Lemay who kindly accepted the invitation to revive it. I am
>> very grateful. Moreover, there is no one better suited to the role and
>> our community is fortunate to have him moderating. I am also very happy
>> that the new home of the list is Macquarie.
>>
>> Best wishes to everyone. I am hoping to see many of you in the not
>> distant future, Bob Rosebrugh
>>
>>
>>
>> ----------
>>
>> You're receiving this message because you're a member of the Categories
>> mailing list group from Macquarie University.
>>
>> Leave group:
>> https://protect-au.mimecast.com/s/k8poCwV1jpS6J5YWIVTAc0?domain=outlook.office365.com<https://protect-au.mimecast.com/s/jByGC91W8rCn73nOSEZzhG?domain=outlook.office365.com>
>


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Re: Signing off

[Peter LeFanu Lumsdaine]

[-- Attachment #1: Type: text/plain, Size: 4910 bytes --]

Just writing to add one more voice of gratitude to the chorus — thanks, Bob, for all the diligent and tactful moderation work, keeping the mailing list running fruitfully for longer now than many (?most) of us have been in the field.  It’s been a model of moderation, keeping things civil and on-topic without discouraging people from wide-ranging and often lively discussion — a difficult balancing act that’s often unnoticed as long as it’s maintained!

With much appreciation,
–Peter.




On Sun, Oct 29, 2023 at 8:22 PM George Janelidze <janelg@telkomsa.net<mailto:janelg@telkomsa.net>> wrote:
Dear Bob,

Let me join Lauchie and all others who greatly appreciated, saying it loudly or not, what your so big, intelligent, and kind work did to our community. Instead of "we will miss you" I want to say "see you" because I hope we will communicate with you and see you, at least on CT conferences, as before.

Thank you so much, and
Very best regards to you,
George

From: johnm@math.ubc.ca<mailto:johnm@math.ubc.ca>
Sent: Friday, October 27, 2023 6:30 AM
To: Bob Rosebrugh<mailto:rrosebru@mta.ca>
Cc: categories@mq.edu.au<mailto:categories@mq.edu.au> ; johnm@math.ubc.ca<mailto:johnm@math.ubc.ca>
Subject: Re: Signing off


Dear Bob,

Your service over these many years has been greatly appreciated. It has
promoted many valuable connections for me and was of the utmost help to me
when holding many CT and FMCS conferences in Vancouver. I am glad to see
that this valuable forum for category theory has been transferred so
smoothly and will hopefully continue for many years to come.

Regards,

Lauchie MacDonald


>> On Oct 26, 2023, at 15:52, Bob Rosebrugh <rrosebru@mta.ca<mailto:rrosebru@mta.ca>> wrote:
>>
>> 
>> Dear Colleagues,
>>
>> From March 1990 until recently it was my privilege to moderate the
>> categories mailing list. For a couple of years it has been my intention
>> to pass the list to a new moderator, but I was too slow to act. Changes
>> to IT service at my former employer, Mount Allison University, abruptly
>> made it impossible for me to continue running the list.
>>
>> Those changes were unexpected for me, but I have been away from the
>> campus for over three years and was not aware. The IT staff at Mount
>> Allison have always been very supportive of the list and I thank them
>> for their more than three decades of generous assistance.
>>
>> It is a reassuring pleasure to know that the list is now in the capable
>> hands of JS Lemay who kindly accepted the invitation to revive it. I am
>> very grateful. Moreover, there is no one better suited to the role and
>> our community is fortunate to have him moderating. I am also very happy
>> that the new home of the list is Macquarie.
>>
>> Best wishes to everyone. I am hoping to see many of you in the not
>> distant future, Bob Rosebrugh
>>
>>
>>
>> ----------
>>
>> You're receiving this message because you're a member of the Categories
>> mailing list group from Macquarie University.
>>
>> Leave group:
>> https://protect-au.mimecast.com/s/k8poCwV1jpS6J5YWIVTAc0?domain=outlook.office365.com<https://protect-au.mimecast.com/s/kx6vCYW86EsYv0Lou0BgNi?domain=outlook.office365.com>
>


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[-- Attachment #2: Type: text/html, Size: 13176 bytes --]

Re: Signing off

[Joyal, André]

[-- Attachment #1: Type: text/plain, Size: 5497 bytes --]

Dear Bob,

I would like to join my voice to the chorus: your contribution to  the life of the community of category theorists cannot be priced. There was a lot of wisdom in your actions as a moderator. I am glad you have resisted me occasionally.

Best wishes,
André
________________________________
De : Peter LeFanu Lumsdaine <p.l.lumsdaine@gmail.com>
Envoyé : 1 novembre 2023 12:17
À : George Janelidze <janelg@telkomsa.net>
Cc : Bob Rosebrugh <rrosebru@mta.ca>; categories@mq.edu.au <categories@mq.edu.au>; MacDonald John <johnm@math.ubc.ca>
Objet : Re: Signing off

Just writing to add one more voice of gratitude to the chorus — thanks, Bob, for all the diligent and tactful moderation work, keeping the mailing list running fruitfully for longer now than many (?most) of us have been in the field.  It’s been a model of moderation, keeping things civil and on-topic without discouraging people from wide-ranging and often lively discussion — a difficult balancing act that’s often unnoticed as long as it’s maintained!

With much appreciation,
–Peter.




On Sun, Oct 29, 2023 at 8:22 PM George Janelidze <janelg@telkomsa.net<mailto:janelg@telkomsa.net>> wrote:
Dear Bob,

Let me join Lauchie and all others who greatly appreciated, saying it loudly or not, what your so big, intelligent, and kind work did to our community. Instead of "we will miss you" I want to say "see you" because I hope we will communicate with you and see you, at least on CT conferences, as before.

Thank you so much, and
Very best regards to you,
George

From: johnm@math.ubc.ca<mailto:johnm@math.ubc.ca>
Sent: Friday, October 27, 2023 6:30 AM
To: Bob Rosebrugh<mailto:rrosebru@mta.ca>
Cc: categories@mq.edu.au<mailto:categories@mq.edu.au> ; johnm@math.ubc.ca<mailto:johnm@math.ubc.ca>
Subject: Re: Signing off


Dear Bob,

Your service over these many years has been greatly appreciated. It has
promoted many valuable connections for me and was of the utmost help to me
when holding many CT and FMCS conferences in Vancouver. I am glad to see
that this valuable forum for category theory has been transferred so
smoothly and will hopefully continue for many years to come.

Regards,

Lauchie MacDonald


>> On Oct 26, 2023, at 15:52, Bob Rosebrugh <rrosebru@mta.ca<mailto:rrosebru@mta.ca>> wrote:
>>
>> 
>> Dear Colleagues,
>>
>> From March 1990 until recently it was my privilege to moderate the
>> categories mailing list. For a couple of years it has been my intention
>> to pass the list to a new moderator, but I was too slow to act. Changes
>> to IT service at my former employer, Mount Allison University, abruptly
>> made it impossible for me to continue running the list.
>>
>> Those changes were unexpected for me, but I have been away from the
>> campus for over three years and was not aware. The IT staff at Mount
>> Allison have always been very supportive of the list and I thank them
>> for their more than three decades of generous assistance.
>>
>> It is a reassuring pleasure to know that the list is now in the capable
>> hands of JS Lemay who kindly accepted the invitation to revive it. I am
>> very grateful. Moreover, there is no one better suited to the role and
>> our community is fortunate to have him moderating. I am also very happy
>> that the new home of the list is Macquarie.
>>
>> Best wishes to everyone. I am hoping to see many of you in the not
>> distant future, Bob Rosebrugh
>>
>>
>>
>> ----------
>>
>> You're receiving this message because you're a member of the Categories
>> mailing list group from Macquarie University.
>>
>> Leave group:
>> https://protect-au.mimecast.com/s/k8poCwV1jpS6J5YWIVTAc0?domain=outlook.office365.com<https://protect-au.mimecast.com/s/pr1BCQnM1WfVKY16uxTqU6?domain=outlook.office365.com>
>


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Defining composition via colimit

[Jamie Vicary]

Dear all,

In a current project we have the following situation. For a category
we are attempting to define, we know what the objects are, and also
the morphisms. Unfortunately we do not have an obvious composition
operation. What we do have is a "colimit" operation, which operates on
a directed graph labelled by our objects and morphisms, and returns a
putative colimit object equipped with a family of morphisms in the
usual way (or fails.)

We then define the composite of morphisms A->B,  B->C  to be the
colimit of the diagram A->B->C. We then check that this composition
operation satisfies the axioms of a category, and that our earlier
colimit construction is indeed an actual colimit with respect to the
compositional structure. It seems that everything works fine, and we
are happy.

My question is whether this has any precedent in the literature. The
situation as I have described it is a bit simplified, in reality there
is some higher categorical stuff going on. Personally I'm sure I've
read similar things in the literature in the past but I can't track
them down now that I actually need them. The nLab article on
"composition" has some stuff about this with regard to transfinite
composition, but we're not trying to do anything transfinite here.

Best wishes,
Jamie



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Re: Defining composition via colimit

[Richard Garner]

Hi Jamie,

That does sound interesting. Did you look at:

- Kelly, G. M., & Le Creurer, I. J. On the monadicity over graphs of
  categories with limits. Cahiers de Topologie et G\'eom\'etrie
  Diff\'erentielle Cat\'egoriques, 1997(38), 179–191.

This paper, among other things, shows that categories with limits
indexed by finite acyclic directed graphs are monadic over directed
graphs. It seems like you could be describing an algebra structure for
this monad (which is a fortiori a category). The paper gives a fairly
explicit presentation of this monad by generators and relations, so you
should be able to check fairly easily if that is indeed what is going
on.

Richard






Jamie Vicary <jamievicary@gmail.com> writes:

> Dear all,
>
> In a current project we have the following situation. For a category
> we are attempting to define, we know what the objects are, and also
> the morphisms. Unfortunately we do not have an obvious composition
> operation. What we do have is a "colimit" operation, which operates on
> a directed graph labelled by our objects and morphisms, and returns a
> putative colimit object equipped with a family of morphisms in the
> usual way (or fails.)
>
> We then define the composite of morphisms A->B,  B->C  to be the
> colimit of the diagram A->B->C. We then check that this composition
> operation satisfies the axioms of a category, and that our earlier
> colimit construction is indeed an actual colimit with respect to the
> compositional structure. It seems that everything works fine, and we
> are happy.
>
> My question is whether this has any precedent in the literature. The
> situation as I have described it is a bit simplified, in reality there
> is some higher categorical stuff going on. Personally I'm sure I've
> read similar things in the literature in the past but I can't track
> them down now that I actually need them. The nLab article on
> "composition" has some stuff about this with regard to transfinite
> composition, but we're not trying to do anything transfinite here.
>
> Best wishes,
> Jamie