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36
Are all finite-dimensional algebras of a fixed dimension over a field isomorphic to one another?
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15
$6!\cdot 7!=10!$. Is there a natural bijection between $S_6\times S_7$ and $S_{10}$?
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13
Wrong but fun and/or useful "proofs" in linear algebra
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11
Solving the complex equation $(1+z)^5=z^5$
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10
Is it possible to tile a $13 \times 13$ board with $4 \times 1$ dominoes such that the center square is left untiled?
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10
Normal subgroup of a characteristic subgroup
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9
What is $\pi_3(S^2\times S^1)$?
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9
Is the sum of elements of a nontrivial subgroup of $\mathbb Z_p^*$ zero?
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8
Alternating sum involving reciprocals of powers of primes equals $\ln(\frac{\pi}{4})$
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7
Does the category of local rings with residue field $F$ have an initial object?
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7
a linear map on $W$
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7
Find the primes $p$ and $q$ if $n = pq = 14647$ and $\phi(n) = 14400$
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7
Solving $x^{100}− y^{100 }= 100!$
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7
Are $\sin x$, $\sin(x + \frac{\pi}{6})$, and $\sin(x + \frac{\pi}{3})$ linearly independent?
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7
Triviality of a tautological bundle
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7
Localization and Field
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6
Number of ways of arranging 10 tiles in four colors such that any consecutive block of 5 tiles contain all four colors
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6
Contravariant functor taking every finite group to an isomorphic group
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6
Let $f(n)$ be the number of ways to 'completely partition' $S$. Find an expression for $f(n)$ (preferrably with non-recursive arguments)
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6
G acts effectively implies $ dim(G) \leq \frac{n(n+1)}{2} $
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6
Proving that existence of injection $f : S\to \mathbb{N}$ implies $S$ is countable?
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6
Is the set of “Pythagorean” square roots dense in $\left[0, \infty\right)$?
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5
Irreducible representation is injective
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5
Why does $A_s = k[U,T,S]/(UT-S) \otimes_{k[S]} k[S]/(S-s)$ simplify to $ A_s = k[U,T] / (UT-s)$?
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5
Homology of Torus with two discs glued on the inside
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5
Determine order of $\langle(12345),(2354)\rangle$.
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5
Intersection of ideals in polynomial ring
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5
Using an integral to generate rational approximations of $\pi$
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