Hard pigeonhole principle problem.
129492
Choosing $15$ out of $100$ whole numbers with difference of any $2$ divisible by $7$
126543
Combinatorics problem: $n$ people line up to $m$ clubs
105221
Confusion about Satisfiability by a denumerable sequence.
45386
Fibonacci sequence emerging from integer partitioning
136290
a mathematical problem on inequalities
134938
Committee combinatorics
86067
A Variation of the even-town odd-town problem
11824
A maximization problem
94923
Using the Pigeonhole Principle to show that $2$ of any $n+1$ numbers from $\{1,2,\ldots,2n\}$ sum to $2n+1$
25769
Finding all posets on a set
40635
Finding Maximum value of consecutive positive integers with constraints
69748
Semi-Ambiguous Combinatorics Problem
11296
The Monty Hall problem
111954
Computing the cardinality of a combinatorial set
92249
Every finite set contains its supremum: proof improvement.
44620
Reference for combinatorial game theory.
69827
Set conditions at a permutation