🌐EnglishEnglishDeutschFrançaisPolskiPortuguêsSvenskaالعربيةفارسی中文日本語EntityQ3240280· pop 20· linked from 10 articlesdirect proofWay of arriving to a mathematical proofAvailable in 20 languagesFrançaisDeutsch中文PortuguêsالعربيةBanglaCatalanCzechMacedonianPolskiConnectionsreductio ad absurdumEntitycontrapositionEntityCategoriesLogical truthMathematical proofs