From: "Ellis D. Cooper" <xtalv1@netropolis.net>
To: P.B.Levy@cs.bham.ac.uk,categories@mta.ca,Dusko.Pavlovic@comlab.ox.ac.uk
Subject: Conditions for adjoints -- another variant
Date: Sat, 31 Oct 2009 22:20:56 -0400 [thread overview]
Message-ID: <E1N4ja0-0001eB-Fz@mailserv.mta.ca> (raw)
Dear categorists,
I cannot resist wondering whether it has been observed that (almost)
everything is a prism, including the Subject, and there is a
generalization of category theory beyond homsets with merely two
parameters. I have omitted a lot of labels because anyone on this
list can fill them in, and I have omitted prisms for identity
diagrams for the same reason. Dotted arrows are induced, outer
squares commute. (By "semi-adjoint" I mean the family of set maps in
either of the two directions in the usual bifunctor definition of adjoint.)
Composition
\xymatrix{ &a\ar[dl]_f\ar@{..>}[dd]^{gf}\\a'\ar[dr]_g&\\&a''}
Functor prism
\xymatrix{
a\ar@{..>}[rr]^{gf}\ar@{|->}[ddd]\ar[dr]_f&&a''\ar@{|->}[ddd]\\
&a'\ar[ur]_g\ar@{|->}[d]&\\
&Fa'\ar[dr]_{Fg}&\\
Fa\ar[ur]_{Ff}\ar@{..>}[rr]_{Fgf}&&Fa''\\
}
Natural Transformation prism
\xymatrix{
Fa\ar[rr]^{\eta_a}\ar@{..>}[ddd]_{Ff}&&Ga\ar@{..>}[ddd]^{Gf}\\
&a\ar@{|->}[ul]\ar@{|->}[ur]\ar[d]^f&\\
&a'\ar@{|->}[dl]\ar@{|->}[dr]&\\
Fa'\ar[rr]_{\eta_{a'}}&&Ga'\\
}
Semi-adjoint prism
\xymatrix{
(Fa\:Gb)\ar[rr]\ar@{..>}[ddd]&&(Ka\:Lb)\ar@{..>}[ddd]\\
&(a\:b)\ar@{|->}[ul]\ar@{|->}[ur]\ar[d]&\\
&(a'\:b')\ar@{|->}[dl]\ar@{|->}[dr]&\\
(Fa'\:Gb')\ar[rr]&&(Ka'\:Lb')
}
Generalized associativity prism
\xymatrix{
(a_1\cdots
a_n)\ar@{..>}[rr]^{(hg)f}\ar[dr]_f\ar[ddd]_1&&(a'''_1\cdots a'''_n)\ar[ddd]^1\\
&(a'_1 \cdots a'_n)\ar@{..>}[ur]_{hg}\ar[d]^g&\\
&(a''_1\cdots a''_n)\ar[dr]_h&\\
(a_1\cdots a_n)\ar@{..>}[ur]_{gf}\ar@{..>}[rr]_{h(gf)}&&(a'''_1\cdots a'''_n)
}
Generalized semi-adjoint
\xymatrix{
(F_1a_1\cdots F_na_n)\ar[rr]\ar@{..>}[ddd]&&(G_1a_1\cdots
G_na_n)\ar@{..>}[ddd]\\
&(a_1\cdots a_n)\ar@{|->}[ul]\ar@{|->}[ur]\ar[d]&\\
&(a'_1\cdots a'_n)\ar@{|->}[dl]\ar@{|->}[dr]\\
(F_1a'_1\cdots F_na'_n)\ar[rr]&&(G_1a'_1\cdots G_na'_n)
}
Ellis D. Cooper
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next reply other threads:[~2009-11-01 2:20 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-01 2:20 Ellis D. Cooper [this message]
-- strict thread matches above, loose matches on Subject: below --
2009-11-09 23:50 Ellis D. Cooper
2009-10-25 10:05 Paul Levy
2009-10-25 1:03 Dusko Pavlovic
2009-10-24 23:11 robin
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