Cardinality of ring having more than one left inverse for some element!
107378
If a ring element is right-invertible, but not left-invertible, then it has infinitely many right-inverses.
35034
Multiplicative inverses for $Z_n$
18066
Prove that any non-zero-divisor of a finite dimensional algebra has an inverse
111954
Computing the cardinality of a combinatorial set
99567
Proving that an inverse ring homomorphism of an ideal is an ideal?
95373
Additive set function on a semiring of sets
158426
Proving lemma about centrality of idempotent elements in a Ring with no nilpotent elements.
144735
Possible cardinality of power sets
142631
Show that A has the same cardinality as $A\setminus\{x,y,z\}$
46698
Showing a set is closed under inverses
62687
Proving Cardinality of Cosets in Abstract Algebra
113109
Showing that a map is bijective and finding its inverse
67451
Building a bijection from a finite union of countable sets to $\mathbb{N}$
14873
$1+a$ and $1-a$ in a ring are invertible if $a$ is nilpotent
67554
In a group, the number of non-self-inverse elements is even
37951
proof detail concerning bijection between a set and its power set
108330
Product of all elements in finite abelian group equals its own inverse