Groups without matrix representation?
43326
Can every group be represented by a group of matrices?
156342
When we can say a group can not be abelian
127664
Inverse elements in the absence of identities/associativity.
85222
Direct sum of finitely-many non-abelian groups
129345
Name for matrices with orthogonal (not necessarily orthonormal) rows
135241
Show that $\mathbb{Z}/n^2\mathbb{Z}$ is not isomorphic to other group
102246
Are there nonsmooth Lie groups?
46843
A ring without the Invariant Basis Number property
75104
Existence of some type matrix
121636
General linear group of a vector space
8066
Sort-of-simple non-Hopfian groups
139025
Do all Groups have a representation?
156549
Prove that there is no group $G$ s.t. $\operatorname{Aut}(G)=\mathbb{Q}$
40222
Matrices that are not diagonal or triangular, whose eigenvalues are the diagonal elements
141833
Is it possible to construct a quasi-vectorial space without an identity element?
120254
Nowhere commutative semigroups = rectangular bands?
29538
Does a non-abelian semigroup without identity exist?