Check my proof. Is this a group?
1315
Let $R$ be a ring. Define a circle composition ◦ in R by $a ◦ b =a+b-ab$, $a, b ∈ R$.
33196
show that A(T) is a group under operation of composition of functions
92430
Show that the group is cyclic.
100399
A doubt with a part of a certain proof.
150854
Identifying a quotient group (NBHM-$2014$)
117414
How would I prove what elements $S_3$ contains, and what its subgroups are?
92057
Prove that for every odd integer n, there is a group...
79933
Let $G$ be a group and $c\in G$. Define $*$ on $G$ by: $x*y=xdy$ for all $x,y\in G$, where $d$ is the inverse of $c$. Prove $(G,*)$ is a group.
101596
Determine group G as cyclic
121141
Proving Finiteness of Group from Presentation
84985
Is a semigroup with unique right identity and left inverse a group?
112407
Set of left cosets is a group
114522
Prove that identity is unique in a group
11003
Proving that $G/N$ is an abelian group
15210
Group of order 6 proof
115849
Are the Groups having all subgroups of same order conjugate classified?
146952
When can I say that $\cup H_i$ is a group?