ineff

2,273 reputation

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bio	website	poisson.phc.unipi.it/~mossa
	location	Earth
	age	25
visits	member for	1 year, 11 months
	seen	21 mins ago
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I'm math student, in particular I'm interested in algebra, geometry, topology and category theory (especially higher dimensional category theory) and its application in mathematics.

	2,273 reputation	bio	website	poisson.phc.unipi.it/~mossa	visits	member for	1 year, 11 months
1213 badges		location	Earth		seen	21 mins ago

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Dec 8	comment	semidirect product, split extension Fine, give me one moment I change my answer, but allow me to use my notation.
Dec 8	answered	semidirect product, split extension
Dec 1	comment	Reasons for coherence for bi/monoidal categories thanks to the answer, I realized that probably my question didn't address my doubts so I've edited it.
Dec 1	comment	Reasons for coherence for bi/monoidal categories @ZhenLin Thanks for the comment, I completely agree with what you said, I realize my question wasn't addressing my doubt, I've edited the question, hope I've made myself more clear.
Dec 1	revised	Reasons for coherence for bi/monoidal categories Added some specifications
Nov 30	asked	Reasons for coherence for bi/monoidal categories
Nov 23	comment	Group actions, permutation representations and currying These are just some few reasons which explain why both the definitions are important, probably there are many more which I've forgotten, but I'm sure you're going to get a better understanding of these relations and their importance in particular when you're going to start to deal with ring/algebras representations and modules over said algebras, which are the ring version of group representations and actions.
Nov 23	comment	Group actions, permutation representations and currying Actions are less group theoretic than homomorphism (at least for what's my taste), anyway in practice actions arise more naturally than representations, and they gives us a incredible beautiful and useful symbolism to deal with representations (at this point is clear that studying representations of a group is the same as studying its actions).
Nov 23	comment	Group actions, permutation representations and currying @SJGreen you're welcome. About your last comment on the comparison between homomorphisms (but I prefer talk about representations) and actions: as you have already said they both have different advantages. Representations are good objects for theoretical reasons: they allows to deal with actions in terms of the objects of group theory (i.e. groups and group homomorphisms). This is useful because it enables to use general results about group to prove facts about actions and the other end.
Nov 22	answered	Group actions, permutation representations and currying
Nov 22	revised	Adjoining an element to a ring Completed answer
Nov 22	comment	Adjoining an element to a ring Right @YACP. Now I complete :) thanks.
Nov 21	comment	Adjoining an element to a ring Simple: $2x - 6 = 2(x - 10) + 14$ and clearly $14 = (2x - 6) - 2(x - 10)$, so we have that $2x - 6, x - 10 \in (x - 10, 14)$ and, on the other end $14, x - 10 \in (x - 10, 2x - 6)$ so these two ideals are one contained in the other one, and so they're equal.
Nov 21	answered	Adjoining an element to a ring
Oct 24	answered	A collection of Isomorphic Groups
Oct 20	comment	A model structure on $\bf Cat$ Just as a comment: every functor from a category to the one object-one morphism category is a fibration but it doesn't reflect iso, generally.
Oct 3	comment	Homotopic maps which aren't relative homotopic Ok,now I get it thanks @mercio .
Oct 3	accepted	Homotopic maps which aren't relative homotopic
Oct 1	accepted	What is combinatorics?
Oct 1	comment	Homotopic maps which aren't relative homotopic @mercio you're right sorry, here're the problems. in the second paragraph there's a homotopy $\bar h$ which is defined as $\bar h(x) = \dots$ instead of something like $\bar h(x,t) = \dots$, and it's also not clear (at least to me) why this map should be continuous, it doesn't seem to me that we can apply the gluing lemma.