Inverse element in associative structure not necessarily unique
107900
A ring which has many distinct left inverses
128867
Inverse of order preserving transformation
44405
Prove XOR is commutative and associative?
39788
$a+1,a-1$ invertible for nilpotent element
133498
Show that Function Compositions Are Associative
94855
Prove if a (mod n) has a multiplicative inverse, then it's unique
10908
Associated elements in a ring
3217
Construction of uncountably many non-isomorphic linear (total) orderings of natural numbers
140190
Binary operation $xy$, has identity, but not associativity. Is the inverse unique?
48308
Uniqueness of radix representation of integers in base 3
105818
Given an associative $F$-algebra do there necessarily exist elements $a_1,a_2 \in K$ satisfying $a_1*a_2=a$?
102383
Associativity of Cartesian Product
134588
Seeking a direct proof about nested inclusions
152191
Why is a monoid with right identity and left inverse not necessarily a group?
42467
Inverse of an invertible triangular matrix (either upper or lower) is triangular of the same kind
12459
Associativity of symmetric difference of sets
110014
Right Inverse for Surjective Function