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Flaška, V.; Ježek, J.; Kepka, T.; Kortelainen, J. Transitive Closures of Binary Relations I(PDF). Prague: School of Mathematics - Physics Charles University. 2007: 1 [2013-08-20]. （原始内容(PDF)存档于2013-11-02）. Lemma 1.1 (iv). Note that this source refers to asymmetric relations as "strictly antisymmetric".
web.archive.org
Flaška, V.; Ježek, J.; Kepka, T.; Kortelainen, J. Transitive Closures of Binary Relations I(PDF). Prague: School of Mathematics - Physics Charles University. 2007: 1 [2013-08-20]. （原始内容(PDF)存档于2013-11-02）. Lemma 1.1 (iv). Note that this source refers to asymmetric relations as "strictly antisymmetric".
