1 February 2018:
1) Today this paper by Daniel Cicala was published in TAC!
* Daniel Cicala, [Spans of cospans](http://www.tac.mta.ca/tac/volumes/33/6/33-06abs.html).
Abstract. We study spans of cospans in a category C and explain how to horizontally and vertically compose these. When C is a topos and the legs of the spans are monic, these two forms of composition satisfy the interchange law. In this case there is a bicategory of objects, cospans, and `monic-legged' spans of cospans in C. One motivation for this construction is an application to graph rewriting.
2) Blake Pollard has applied for a 2-year National Research Council
fellowship at the place he's already working now, the National Institute of Standards and Technology.
3) Blake also applied to Google's AI Residency Program
Some of you may, someday, want to follow suit and apply for these yourselves!
4) Brandon and I dealt with the referee's comments on our paper Props in network theory and resubmitted it to Tom Leinster at TAC. It will now go to a second referee who knows more about category theory and probably less about symplectic geometry and electrical engineering.
The first referee had a lot of useful specific comments which I won't show you, but he began with some very negative general comments which I will show you, just so you know that you've got to be tough: don't give up when a referee hates your paper!
Here are the first referee's comments:
The manuscript under review appears to be a part of a program of John Baez and his
collaborators to understand networks of various kinds in terms of morphisms of symmetric
monoidal categories. It seems that the main result is an extension of the black-boxing
theorem of Baez and Fong, Theorem 49. The authors never explicitly state what the main
result of the paper actually is.
I wish the authors had spent more time explaining what they are doing and why. Having
an actual example of the black-boxing functor applied to a circuit would have been useful
as well as well. (While the paper contains paragraphs labeled as "example" they are really
constructions and short propositions and not really illustrative examples.)
There are hints in the paper scattered here and there that the results should have applica-
tions in engineering either as mathematical models of the bond graph formalism or as a new
mathematical approach to the behavioral point of view of systems as advocated by Willems.
Unfortunately the authors never explicitly engage with the current bond graph literature.
In particular the authors ignore (or are unaware of?) port-Hamiltonian systems, a popular
modern version of the bond graph formalism. Willems is mentioned briefly (not by name):
"In general, engineers have found the relation between electrical circuits and signal-flow
diagrams rather problematic ." Having called engineers stupid the authors fail to explained
why their approach is superior.
I am put off by the style of writing. The paper reads like a series of blog posts where a
reader is invited to come along on a long and interesting journey with a number of side trips.
Easy things are explained at length while harder arguments are swept under the rug or left
vague or put in an appendix. There are white lies scattered here and there which are not
entirely benign. It is never clear what audience the authors are writing for.
To conclude: the paper is too long, unfocused and unclear. It needs to be re-written and
in particular, shortened, before it could be considered for publication in TAC.
Luckily Tom Leinster realize that the first referee was being a bit unreasonable, in particular by saying
I wish the authors had spent more time explaining what they are doing and why
the paper is too long... It needs to be re-written and in particular, shortened
So, he's giving us a second chance with another referee. Bruised but not defeated, we live on to fight another day!