# All Questions

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### Existence of internal Homs and equivalence of monoidal categories

Let $(\mathcal{C}, \otimes)$ and $(\mathcal{D}, \otimes')$ be two monoidal categories which are monoidaly equivalent. Assume $\mathcal{C}$ has internal Homs, that is, Hom$(X,1_{\mathcal{C}})$ can be ...
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### Discrete random walk with uniformly distributed transition p, set initially

I've been working on a discrete version of the "unreliable friend" distribution. It would seem that what I've come up with is equivalent to the following random walk: Choose $p$ from $U(0,1)$ Start ...
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### Is there any $ABCDS$ pyramid (where $ABCD$ is a rectangle) in which each 2 edges have different lengths and $|AS|+|CS|=|BS|+|DS|$? [on hold]

I had geometry quite a while ago and I wonder if anyone has any idea how to tackle this problem: Is there any $ABCDS$ pyramid (where $ABCD$ is a rectangle) in which each 2 edges (except for the base) ...
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### Variant of (WEAK) PARTITION with 2 distinct solutions

I am interested in the complexity of the following problem: Input: A list $a1\leq ⋯ \leq a_n$ of positive integers. Question: Are there two vectors $x, x'\in\{−1,0,1\}^n$ such that ...
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### Spin Structures for Quaternionic-Kaehler and Hyper-Kaehler Manifolds

As is well-known (see Friedrich's book for example) every Kähler manifold is spin (or at least spin$^c$) and the Dirac is given (up to a twist) by $\partial + \partial^*$. What happens in the ...
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### Forcings that are not equivalent to Levy collapse

Assume GCH and that $\kappa$ is a regular uncountable cardinal. Let $\mathbb{P}$ be a $<\kappa$-directed closed, nowhere trivial, $\kappa^+$-cc poset of size $\kappa^+$. Must $\mathbb{P}$ be ...