small category- alternative
Definition 0.1.
A (small) category consists of a set of objects and a set of arrows together with the following structure
:
- •
a source map assigning an object to each arrow ,
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a target map: assigning an object t(f) to each arrow ,
- •
an identity map assigning to each object an arrow with
- •
a composition map assigning to each pair of arrows , such that
, a third arrow with and .
- •
The composition thus defined “” is associative, that is,
whenever these compositions make sense.
- •
the identity map satisfies for any such that and , and any such that .
References
P. A. Zito. 2008. [arXiv: math.CT].http://arxiv.org/PS_cache/math/pdf/0509/0509266v1.pdf2- -Categories with non-simple units.,(Preprint).