Stephan Müller
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Registered User
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Apr 4 |
answered | cryptographic primitive process |
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Feb 18 |
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Diff(M) and connectedness I guess the question is a bit vague. Is Diff(M) the subsheaf of C(M) of smooth functions on M? Clearly, if Diff(M) has non-trivial idempotents, so has C(M). Are you asking for the converse? |
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Feb 7 |
comment |
Notation for the subobject classifier Maybe they had the christian 'alpha & omega' in mind. And the characteristic functions, as well as the true arrow end in omega. |
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Feb 5 |
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Non-zero monoid Thanks, your are right. Somehow I missed that. I am not sure if the OP has such answers in mind, but here [ maths.manchester.ac.uk/~mkambites/events/bmc2008/… ](pdf) is a survey of 'not-so-bad/good' presentations and their word problems. |
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Feb 3 |
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Non-zero monoid wccanard, thanks for pointing this out. I didn't know. Your are probably talking about the 'word problem for groups' ( en.wikipedia.org/wiki/Word_problem_for_groups ). That is given an element in terms of generators, decide whether it is the trivial element. Correct me if i am wrong. Jacks questions is slightly different and asks for the existence of a non-trivial element. This may be much easier. And also the above problem is decidable for many groups and only undecidable 'in worst case'. So it really depends the monoid in consideration. |
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Jan 30 |
awarded | ● Enthusiast |
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Jan 25 |
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Is an additive category a balanced category? A necessary condition for punctured category to be balanced is "every mono is the kernel of some morphism" or dually "every epi is the cokernel of some morphism". In view of this, existence of counterexamples seems much more plausible than if one thinks of an 'almost abelian' setting. ---- And the map n:Z->Z form Eric Wofseys example is not the cokernel of something. |
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Jan 18 |
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NP problem implications That could be math.stackexchange.com but there are many other as well |
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Jan 17 |
revised |
Vertical and Horizontal Isomorphisms in 2-categories added 567 characters in body |
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Jan 17 |
revised |
Vertical and Horizontal Isomorphisms in 2-categories added 21 characters in body |
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Jan 17 |
awarded | ● Editor |
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Jan 17 |
revised |
Vertical and Horizontal Isomorphisms in 2-categories fixed some typos |
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Jan 16 |
answered | Vertical and Horizontal Isomorphisms in 2-categories |
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Jan 15 |
awarded | ● Nice Answer |
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Jan 15 |
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Elementary applications of linear algebra over finite fields This is similar to the card game SET!, see mathoverflow.net/questions/13638/… |
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Jan 15 |
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Proving a determinant = 0 The Lemma is very nice. Thanks for the pointer. But how do you manage to find an easy (directed and weighted) graph representing a given matrix? I know you don't claimed this to be feasible but are some considerations? I can imagine there is a generic algorithm which allows to "rediscover" Leibniz' formula. |
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Jan 14 |
answered | Elementary applications of linear algebra over finite fields |
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Jan 9 |
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Examples of applications that use the Schnorr digital signature? I think this scheme is not widespread because of patent issues. It is similar to DSA which is frequently used. Maybe it is used for some smartcards because of its better performance. It's probably the best to ask again on crypto.stackexchange.com |
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Jan 7 |
accepted | Origin of notion of “split Grothendieck group”? |
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Jan 7 |
awarded | ● Teacher |
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Jan 7 |
answered | Origin of notion of “split Grothendieck group”? |
