Re: "Databases are Categories"

[soloviev@irit.fr]

Hi,

then , in this setting, how coherence should be interpreted?
According to Mac Lane, a coherence theorem asserts commutativity
of a class of diagrams; some other authors mean rather decision
procedure/criteria  for commutativity of diagrams.

By the way, did you consider some kind of "basic" arrows
and generated "canonical maps"? Do there appear/be used
some known types of categories with structure
(cartesian, monoidal, cartesian closed, monoidal closed)?

Another interesting question could be isomorphism of objects.

Best wishes

Sergei Soloviev

  Hi all,
>
> The basic idea of my talk was this: one can think of any category C as a
> "database schema": the objects of C are called "tables" and an arrow
> f:A-->B
> is called a "column of table A with values in table B".  Now a functor
> C-->Sets is a "state" of that database: it fills every table with a set  of
> rows.  Leaf objects of C (objects with no outgoing arrows) correspond to
> "pure data."  One can thus visualize a category as a system of tables;
> commutative diagrams correspond to "rules" such as "the secretary of a
> department must be in that department."
>
> Using sketches instead of categories allows a little more flexibility, but
> the basic idea is as above.  The model is nice for a variety of reasons,
> most of all its simplicity.  In polite contradiction to one of Diskin's
> claims, two database administrators (at two large multi-national
> corporations) that I know think it is a viable model.  They do not balk  at
> the idea of data columns being considered as foreign keys.  It puts
> everything on the same playing field.
>

...

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