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Search problems by topic, difficulty, and proof strategy.
Showing 24 of 24 problems
- Divisible Difference ProcessDifficulty 1number theorydivisibilitymodular arithmeticstrategy: invariantMoves: divisibility invariant, modulo invariantSource: MathLab
- Powers Mod 3 PatternDifficulty 1number theorymodular arithmeticpowersstrategy: modular arithmeticMoves: powers mod n pattern, residue cycleSource: MathLab
- Parity invariant warmupDifficulty 2combinatoricsinvariantsparitystrategy: invariantMoves: parity invariantSource: MathLab
- Parity invariant warmupDifficulty 2combinatoricsinvariantsparitystrategy: invariantMoves: parity invariantSource: MathLab
- Smallest Counterexample PrincipleDifficulty 2combinatoricsproof methodscontradictionstrategy: extremal principleMoves: minimal counterexampleSource: MathLab
- Equal RemaindersDifficulty 2number theorymodular arithmeticpigeonholestrategy: pigeonholestrategy: modular arithmeticMoves: pigeonhole on residuesSource: MathLab
- Coloring InvariantDifficulty 2combinatoricsinvariantscoloringstrategy: invariantMoves: coloring invariantSource: MathLab
- NATIONAL XXX OMA problemDifficulty 3combinatoricscoloringcombinatoricsinvariantsstrategy: invariantMoves: coloring invariantSource: MathNet
- APMO problemDifficulty 3geometrycoloringcombinatoricsgeometryinvariantsstrategy: invariantMoves: coloring invariantSource: MathNet
- AustriaMO2013 problemDifficulty 3geometrygeometrySource: MathNet
- BMO 2016 Short List Final problemDifficulty 3geometrygeometrySource: MathNet
- Baltic Way 1993 problemDifficulty 3combinatoricscoloringcombinatoricsSource: MathNet
- 60th Belarusian Mathematical Olympiad problemDifficulty 3combinatoricscombinatoricsinvariantsstrategy: invariantMoves: modulo invariantSource: MathNet
- 15th Benelux Mathematical Olympiad problemDifficulty 3geometrygeometrySource: MathNet
- None problemDifficulty 3combinatoricscombinatoricsSource: MathNet
- Autumn tournament problemDifficulty 3geometrycombinatoricsgeometrypigeonholestrategy: pigeonholeMoves: simple pigeonholeSource: MathNet
- Canadian Mathematical Olympiad problemDifficulty 3geometrygeometrySource: MathNet
- International Mathematical Olympiad problemDifficulty 3combinatoricscoloringcombinatoricsinvariantsstrategy: invariantMoves: coloring invariantSource: MathNet
- CroatianCompetitions2011 problemDifficulty 3combinatoricscoloringcombinatoricsinvariantsstrategy: invariantMoves: coloring invariantSource: MathNet
- Czech-Polish-Slovak Match problemDifficulty 3geometrygeometrySource: MathNet
- Cesko-Slovacko-Poljsko problemDifficulty 3geometrygeometrySource: MathNet
- Final Round of National Olympiad problemDifficulty 3geometrygeometrySource: MathNet
- A modular invariant warmupDifficulty 3number theorymodular arithmeticinvariantsstrategy: invariantstrategy: modular arithmeticMoves: modulo invariantSource: MathLab
- A pigeonhole principle warmupDifficulty 3combinatoricspigeonholecountingstrategy: pigeonholeMoves: simple pigeonholeSource: MathLab