🌐EnglishEnglishDeutschFrançaisItalianoTiếng ViệtРусскийفارسی中文日本語EntityQ1191750· pop 10· linked from 28 articlesdouble countingtechnique for proving that two expressions are equal by showing that they both count the size of the same setAvailable in 10 languagesFrançaisDeutsch中文РусскийItalianoGalicianHungarianTiếng Việtفارسیvia Wikidata sitelinks · CC0ConnectionsgraphEntitytreeEntityCategoriesEnumerative combinatoricsMathematical proofs