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Matthias Klupsch

I am a mathematician mainly interested in topology, category theory and most of all algebra, especially representation theory.

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52
Are two norms equivalent if they induce the same topology on a vector space?
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16
Group theory: subset of a finite group
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15
$\mathbb{Q}(\sqrt{1-\sqrt{2}})$ is Galois over $\mathbb{Q}$
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12
The set of subsequential limits is closed
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11
Is the unit circle $S^1$ a retract of $\mathbb{R}^2$?
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10
Basic limit calculation
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10
The existence of an eigenvalue of a finite-dim matrix, in a vector space over an arbitrary field.
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9
Free module over a ring with identity with a basis of size $m, \ \forall m \ge n$
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9
Universal property of the quotient group.
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9
Inverse limit and group completion are isomorphic
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8
How the sum of 2 random variables is also a random variable...
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8
Infinite abelian group whose all nontrivial subroups have finite index
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7
$5|\#\text{Gal}(f/\mathbb{Q})\subset S_5 \implies \text{Gal}(f/\mathbb{Q})$ contains a $5$-cycle?
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7
Does the sum of digits of prime number written in base7 never divide by 3?
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7
Does there exist a field ${K[X]}/{(p)}$ where $p$ is reducible?
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7
In a metric Lie algebra, is the orthogonal complement of a Lie subalgebra a Lie subalgebra?
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6
Does this map extend to a unique automorphism of the polynomial ring of an integral domain?
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6
If $(X,\tau)^n$ is Hausdorff, is $(X,\tau)$ also Hausdorff?
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6
I must be misunderstanding bijection on uncountable sets. (As it relates to stereographic projection)
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6
Example of equivalent but not strongly equivalent metrics
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6
A proper subfield of $\mathbb{R}$ must not be connected?
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6
Can every finite-dimensional associative $\mathbb{C}$-algebra be equipped with a submultiplicative norm?
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6
Does the measurability of a set depend on a specific measure or is it "universal"?
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6
Proof any Finite Doubly Transitive Permutation Group containing a transposition is a Full Symmetric Group?
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5
First Isomorphism Theorem
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5
Natural isomorphism $G/(H\cap K)\to G/H\times G/K$?
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5
Haar measure, convolution and involutions
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5
If every non-zero prime ideal of $R[t]$ is maximal then $R[t]$ is $PID$.
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5
Overlapping positive definite block matrices
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5
Showing tensor product of coalgebras is a coalgebra.
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