3 Aug
2008
3 Aug
'08
2:03 p.m.
What about the part that reads: The unique arrow f making this diagram commute is then correspondingly denoted f1 ∐ f2 or f1 ⊕ f2 or f1 + f2 or [f1, f2] This would seem to say that [f,g] and f+g are the same thing -- but if I've understood Derek Elkins' remarks, the latter is the functorial action on arrows while the former is just the mediating arrow. -- _jsn