🌐EnglishEnglishDeutschEspañolFrançaisNederlandsPolskiPortuguêsTürkçeفارسی中文EntityQ798572· pop 16· linked from 25 articlesPost correspondence problemAlso known as Post's correspondence problemundecidable decision problemAvailable in 16 languagesEspañolFrançaisDeutsch中文PortuguêsCzechHebrewIcelandicNederlandsNorwegianConnectionsInternational Standard Book NumberEntitydigital object identifierEntityCategoriesComputability theoryTheory of computationUndecidable problems