{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,7,30]],"date-time":"2025-07-30T16:43:06Z","timestamp":1753893786473,"version":"3.41.2"},"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>A significant sector of coding theory is that of comma-free coding; that is, codes which can be received without the need of a letter used for word separation.  The major difficulty is in finding bounds on the maximum number of comma-free words which can inhabit a dictionary.  We introduce a new class called a self-reflective comma-free dictionary and prove a series of bounds on the size of such a dictionary based upon word length and alphabet size.  We also introduce other new classes such as self-swappable comma-free codes and comma-free codes in q dimensions and prove preliminary bounds for these classes. Finally, we discuss the implications and applications of combining these original concepts, including their implications for the NP-complete Post Correspondence Problem.<\/jats:p>","DOI":"10.37236\/114","type":"journal-article","created":{"date-parts":[[2020,1,11]],"date-time":"2020-01-11T04:35:52Z","timestamp":1578717352000},"source":"Crossref","is-referenced-by-count":2,"title":["Restrictions and Generalizations on Comma-Free Codes"],"prefix":"10.37236","volume":"16","author":[{"given":"Alexander L.","family":"Churchill","sequence":"first","affiliation":[]}],"member":"23455","published-online":{"date-parts":[[2009,2,20]]},"container-title":["The Electronic Journal of Combinatorics"],"original-title":[],"link":[{"URL":"https:\/\/www.combinatorics.org\/ojs\/index.php\/eljc\/article\/download\/v16i1r25\/pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/www.combinatorics.org\/ojs\/index.php\/eljc\/article\/download\/v16i1r25\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2020,1,18]],"date-time":"2020-01-18T03:12:37Z","timestamp":1579317157000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.combinatorics.org\/ojs\/index.php\/eljc\/article\/view\/v16i1r25"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2009,2,20]]},"references-count":0,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2009,1,7]]}},"URL":"https:\/\/doi.org\/10.37236\/114","relation":{},"ISSN":["1077-8926"],"issn-type":[{"type":"electronic","value":"1077-8926"}],"subject":[],"published":{"date-parts":[[2009,2,20]]},"article-number":"R25"}}