Prob. 19, Sec. 2.3, in Herstein's TOPICS IN ALGEBRA, 2nd ed: Bracketing any $n$-tuple of elements in a set with an associative binary operation
2162
How does one actually show from associativity that one can drop parentheses?
153128
Proof of associativity of convolution
33233
Need to prove that $(S,\cdot)$ defined by the binary operation $a\cdot b = a+b+ab$ is an abelian group on $S = \Bbb R \setminus \{-1\}$.
71902
How to define binary operation on arbitrary set in order to create a group structure.
75017
Definition of General Associativity for binary operations
9651
Cardinality of cartesian product of an infinite set with N
146436
Cardinality of the set of bijective functions on $\mathbb{N}$?
156089
Why is the associative property valid for modular arithmetic?
133762
A set which satisfies all conditions for a Group except associativity
148824
Is associative binary operator closed on this subset?
111032
Proof of Sets involving the Cartesian Product
111951
Prove $\binom{n}{m}\binom{m}{k} = \binom{n}{k}\binom{n-k}{m-k}$
109219
How do the sets $\emptyset\times B,\ A\ \times \emptyset, \ \emptyset \times \emptyset $ look like?
117761
When is $\binom{n}{k}$ divisible by $n$?
148493
Are all n-ary operators simply compositions of binary operators?
97878
Are there uncountably many surjections from $\mathbb N$ to $\mathbb N$?
118674
Simple upper bound for $\binom{n}{k}$