Pigeonhole Principle + Strong Induction: Slicing brownies both directions
66474
Cutting a rectangle into squares
81567
Pigeon hole principle to prove $a-b=9$ in subset.
58481
Exclusion Inclusion Principle Induction Proof
135408
Solving permutation problem sequentially.
5448
Finding the closure of some subsets of the ordered square
149266
Possible distinct binary tree structures at depth d
71918
Mathematical Induction
25496
Avoiding proof by induction
53056
natural deduction: introduction of universal quantifier and elimination of existential quantifier explained
11296
The Monty Hall problem
6113
Proof of Strong principle of Induction (T. Tao Analysis I)
137012
Mathematical Induction for Recurrence Relation
104349
Proof by induction involving symmetric groups
121575
Meet-in-the-middle with checking complexity
86122
Learning roadmap for additive combinatorics
92249
Every finite set contains its supremum: proof improvement.
68882
Path to Combinatorics Problem [$1.11$]