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Computational complexity

3 artículos
P versus np problemNp completeNp complexityP complexityR complexityPolynomial hierarchyExponential hierarchyPolynomial timeExponential timeCooks theoremTime hierarchy theoremSpace hierarchy theoremBoolean satisfiability problemTrue quantified boolean formulaCounting problem complexityInteractive proof systemNatural proofTime complexitySpace complexityP vs npNp completenessAssignment problemCnf satCollision problemConstraint satisfactionExact coverStable matching problemSubgraph isomorphism problemSubset sum problemTraveling salesman problemParameterized approximation algorithmPadding argumentAanderaa karp rosenberg conjectureAnalysis of algorithmsApproximation algorithmAsymptotic computational complexityAveraging argumentBest worst and average caseBoolean circuitCircuit complexityClaw finding problemCobhams thesisCommunication complexityComputation treeComputational complexity of mathematical operationsComputational complexity of matrix multiplicationConfiguration graphComputational resourceComputing the permanentDecision tree modelExistential theory of the realsGap hamming problemGeneric case complexityGeometric complexity theoryGraph isomorphism problemHamiltonian complexityHardness of approximationHartmanis stearns conjectureInformation based complexityLog rank conjectureParameterized complexityPebble gamePseudo polynomial transformationQuasi polynomial growthSmoothed analysisStrong np completenessSwitching lemmaTractable problemUnique games conjectureWeak np completenessYaos principleCircuit computer scienceBig o notation

Twelve Marbles, Three Weighings, and Twenty-Seven Ways to Land

Twenty-four possible answers against 3^3 = 27 outcome sequences leaves just enough room, and four against four splits those answers into exactly 8, 8 and 8. Six against six always tips, so it wastes the level outcome and leaves twelve answers for nine remaining sequences, which makes halving impossible rather than merely slow. The counting argument bounds outcome sequences rather than strategies, so it rules out every adaptive continuation at once, and the explicit schedule closes the positive half.

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23 personas bastan para un cumpleaños compartido, y 253 parejas lo explican

La respuesta refleja ronda las 180, la mitad del calendario. El umbral real es 23, porque una coincidencia necesita una pareja y 23 personas cargan con 253. El mismo razonamiento sitúa la pregunta « ¿alguien comparte MI cumpleaños? » en 253 personas, once veces más gente, y el umbral en raíz cuadrada que hay detrás de ambas explica que un identificador aleatorio de 64 bits se repita tras cinco mil millones de extracciones y no tras dieciocho trillones.

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