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Answers
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29
Are there any nontrivial abelian categories with only finitely many objects?
12
Lifting isomorphisms between derived categories
11
For a monoid with zero $M$, how many additive operations on $M$ can there be making $M$ a ring?
9
Intersection of all normalizers
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Monotonic bijections of rational numbers
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The number in the join of conjugate class and centralizer
6
lenght of a finite group versus number of conjugacy classes of subgroups
6
An operation on binary strings
5
Baer’s criterion for projective modules
5
Exponent of the cohomology of a product of groups
5
About some kind of “converse” of a theorem from Galois theory
5
“Sums-compact” objects = f.g. objects in categories of modules?
5
Standard selfinjective algebras and Auslander-Reiten quiver
4
Stable equivalence and triangle stable equivalence of selfinjective algebras
4
Permutation characters and regular orbits
4
Free Module with a Projective Sub- Module, and Tensor Products
3
Detecting and counting free direct summands
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Free and cellular G-action implies free G-complex?
2
Inductive vs projective limit of sequence of split surjections
2
example re torsionless quotients of abelian groups
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Explicit indecomposable monomorphism of finitely generated non-indecomposable Abelian groups.
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Let $M$ be a $R$-Bimodule that happens to be projective, is its associated left $R \otimes R^{op}$-module projective too?
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Cocomplete but not complete abelian category