All Questions
Tagged with ct.category-theory traces
4 questions
12
votes
1
answer
540
views
Categorical interpretation of disjoint cycle notation for tracing permutations
For a natural number $n\in\mathbb{N}$, let $\underline{n}$ denote the finite set $$\underline{n}:=\{1,2,\ldots,n\}.$$
A permutation $\sigma\in Aut(\underline{n})$ can be uniquely written (up to order) ...
4
votes
1
answer
196
views
Does trace handle composition in a traced symmetric monoidal category?
Suppose that $(C,\otimes,I)$ is a traced symmetric monoidal category (TSMC) with symmetrizor $\sigma$ and trace $Tr$. Given two morphisms $f\colon A\to B$ and $g\colon B\to C$, I can tensor them to ...
8
votes
1
answer
448
views
Ends as a "cotrace" operation on profunctors
As mentioned here, there is a trace operation on the monoidal category of profunctors given by taking coends: for any profunctor $F : A\times X \nrightarrow B \times X$, there is a profunctor $Tr^X(F) ...
15
votes
1
answer
4k
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trace(xy)=trace(yx) in full generality
It is well known that, for square matrix $x$ and $y$, we have $\operatorname{tr}(xy)=\operatorname{tr}(yx)$. Here of course the trace of a matrix is just the sum of the elements of the diagonal.
The ...