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seen Oct 26 at 23:12

Oct
24
comment Colored operads as finitely essentially algebraic theory.
Ok, I think I got it (I misunderstood the finitary condition). Thank you again!
Oct
24
answered Colored operads as finitely essentially algebraic theory.
Oct
24
comment Colored operads as finitely essentially algebraic theory.
Thank for the patience, Zhen Lin. I admit that it is straightforward and this is a way in which I would have made it. Probably there is something I misinterprete, but the definition on nlab requires the signature only to have functional symbols! Further, I thought the signature also have to be a finite set, in oder to be finitely presentable. That is why I have some trouble.
Oct
24
comment Colored operads as finitely essentially algebraic theory.
I have only read the definitions given in the nlab page, hoping that it was accurate enough. (I could not find essentially algebraic theory in the Elephant, although I am quite sure it treats them).
Oct
23
asked Colored operads as finitely essentially algebraic theory.
Sep
30
awarded  Explainer
Jul
2
awarded  Curious
May
29
revised $\mathcal U$ Grothendieck universe. Is $\mathcal{P(U)}$ a model for NBG?
small typo corrected
May
15
comment Hartshorne Problem 1.2.14 on Segre Embedding
Shouldn't you prove that $\mathfrak a$ is actually a homogeneous ideal?
May
14
comment When is $N\otimes_A B \to N$ an isomorphism?
Oh, I think I see: $f$ is also epi iff $B \to B \otimes_A B$ is iso; tensoring by $N\otimes_B-$ (which, as functor, preserves isos) and using the associativity of tensor product we are done.
May
14
comment When is $N\otimes_A B \to N$ an isomorphism?
Nice! Formal because $\colon A \to B$ is epi iff $b\otimes 1_B = 1_B \otimes b$ in $B\otimes_A B$? Or it's even simpler?
May
14
revised When is $N\otimes_A B \to N$ an isomorphism?
edited body
May
14
asked When is $N\otimes_A B \to N$ an isomorphism?
Apr
24
revised Working out the normalization of $\mathbb C[X,Y]/(X^2-Y^3)$
fixed small typo
Apr
24
suggested suggested edit on Working out the normalization of $\mathbb C[X,Y]/(X^2-Y^3)$
Apr
17
comment Are $R=K[a,b,c,d]/(ad-bc, a^2c-b^3, bd^2-c^3, ac^2-b^2d)$ and $K[x^4,x^3y,xy^3,y^4]$ isomorphic?
Great answer! A couple of questions: i) shouldn't it be $I = (a-x^4, \dots )$? ii) is the variable $z$ really needed?
Apr
14
comment Incidence variety fo Grassmmanians
I don't think this is a morphism of varieties, otherwise you could prove, adapting the map, that every subset of a variety should be closed.
Mar
22
accepted Reflexivity of equality in sequent calculus
Mar
10
revised Reflexivity of equality in sequent calculus
Edit: cut rule
Mar
10
asked Reflexivity of equality in sequent calculus