{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,5]],"date-time":"2026-02-05T09:22:17Z","timestamp":1770283337793,"version":"3.49.0"},"reference-count":0,"publisher":"The Electronic Journal of Combinatorics","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Electron. J. Combin."],"abstract":"<jats:p>$S_n(\\pi_1,\\pi_2,\\dots, \\pi_r)$ denotes the set of permutations of length $n$ that have no subsequence with the same order relations as any of the $\\pi_i$.  In this paper we show that $|S_n(1342,2143)|=|S_n(3142,2341)|$ and $|S_n(1342,3124)|=|S_n(1243,2134)|$.  These two facts complete the classification of Wilf-equivalence classes for pairs of permutations of length four.  In both instances we exhibit bijections between the sets using the idea of a \"block\", and in the former we find a generating function for $|S_n(1342,2143)|$.<\/jats:p>","DOI":"10.37236\/1922","type":"journal-article","created":{"date-parts":[[2020,1,11]],"date-time":"2020-01-11T00:11:46Z","timestamp":1578701506000},"source":"Crossref","is-referenced-by-count":12,"title":["Wilf Classes of Pairs of Permutations of Length 4"],"prefix":"10.37236","volume":"12","author":[{"given":"Ian","family":"Le","sequence":"first","affiliation":[]}],"member":"23455","published-online":{"date-parts":[[2005,5,26]]},"container-title":["The Electronic Journal of Combinatorics"],"original-title":[],"link":[{"URL":"https:\/\/www.combinatorics.org\/ojs\/index.php\/eljc\/article\/download\/v12i1r25\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.combinatorics.org\/ojs\/index.php\/eljc\/article\/download\/v12i1r25\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2020,1,17]],"date-time":"2020-01-17T23:49:38Z","timestamp":1579304978000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.combinatorics.org\/ojs\/index.php\/eljc\/article\/view\/v12i1r25"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2005,5,26]]},"references-count":0,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2005,1,7]]}},"URL":"https:\/\/doi.org\/10.37236\/1922","relation":{},"ISSN":["1077-8926"],"issn-type":[{"value":"1077-8926","type":"electronic"}],"subject":[],"published":{"date-parts":[[2005,5,26]]},"article-number":"R25"}}