Operator which is symmetric but not associative?
18817
Does commutativity imply Associativity?
64658
How many associative binary operations for a set of two elements?
71961
Is abstract algebra (mostly?) restricted to $2$-ary operators?
90475
Coordinate-free proof of $\operatorname{Tr}(AB)=\operatorname{Tr}(BA)$?
17217
Linear algebra skew symmetric
133498
Show that Function Compositions Are Associative
103695
Prove Inverses not need be Unique if Associativity fails
117967
Unary operator expected
151752
Example of a linear operator on some vector space with more than one right inverse.
83866
Confusion with Associativity of Assignment operator in C
24139
Logical explanation why exponentiation operation is not commutative and associative
89177
$\operatorname{adj}(AB) = \operatorname{adj} B \operatorname{adj} A$
42835
Example of a relation that is symmetric and transitive, but not reflexive
101512
Is there an numeric arithmetic with a single operator?
74839
Catalan numbers: bijection between applications of a binary operator and Dyck words.
26572
Does the Symmetric difference operator define a group on the powerset of a set?
22297
Normal operator $\Rightarrow$ S invariant implies $S^\perp$ invariant