## All Questions

1k views

### Which rings are subrings of matrix rings?

In this question, all rings are commutative with a 1, unless we explicitly say so, and all morphisms of rings send 1 to 1. Let A be a Noetherian local integral domain. Let T be a …
262 views

### Is there an example of Gibbs measure that is not a weak limit of finite volume Gibbs measure ?

Consider the first neighbors Ising model in $\mathbb Z^2$, with the Hamiltonian in the finite volume $\Lambda\subset\mathbb{Z}^2$ given by  H_{\Lambda}(\sigma|\omega)=-J\sum_{i, …
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### What condition on a “bibundle between categories” generalizes “right-principal bibundle between groupoids”?

My question is long on background and motivation, and almost but not quite answered over at the nLab. I'll write up a bunch before asking my question (feel free to skip to the end …
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### Sequence that converge if they have an accumulation point

I am looking for classes of sequence, that converge iff they contain a converging sub-sequence. The basic example of such sequences are monotone sequences of real numbers. A more …
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### Marginals and Convex Sets

I am looking for a weak convergence of marginals result, in the following type of situation. References to 'related' situations are also very much appreciated. I have a collection …
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### systems of parameters vs. minimal “exhausting” systems in a Noetherian local ring

Hello, Probably this is a very easy question. Fix a Noetherian local ring $A$, and an $A$-module of finite type $M$. Lets call a system $x_1 , \ldots , x_m \in \mathfrak{m}$ $M$ …
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### [solved] sequent calculus as programming language

intuitionistic logic ~ programming natural deduction ~ lambda-calculus Hilbert system ~ combinatory logic {S, K} Gentzen system=sequent calculus ~ ? What would you write in pla …
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### Confusing definitions in Liu’s Algebraic geometry and arithmetic curves?

In Qing Liu's book Algebraic geometry and arithmetic curves I came across several confusing definitions. Several times he defines a notion only for a subclass of schemes/morphisms …
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### The space of compact subspaces of $R^\infty$ homotopy equivalent to a given finite complex.

Let $X$ be a finite (CW or simplicial - doesn't matter) complex and consider the space of all compact subspaces of $R^\infty$ which are homotopy equivalent to $X$, topologized say …
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### Set Theory and Definability

Let $\mathcal{G} = (G,\in)$ be some $\mathfrak{L}$ = {$\in$} structure (for this question a model of ZFC). Let $M$ be some definable class (using Jech's term) and $E$ some class-re …
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### Different forms of compactness and their relation

Given a topological space X one can define several notion of compactness: X is compact if every open cover has a finite subcover. X is sequentially compact if every sequence has …
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### Generalized Fibonacci sequences [closed]

Why Fibonacci sequence start at 0, Tribonacci sequence with 0,0, Tetranacci with 0,0,0, etc. Can this sequences starts at 1. Has any good reasons for that. These sequences arise in …
895 views

### Derived functor

Let $F:A\longrightarrow B$ be a left exact functor of Abelian categories. My question is about the derived functor $RF: D(A)\longrightarrow D(B)$. Let $X$ be an object of $A$. If …