Yoram Hirshfeld Alexander Moshe Rabinovich Logics for Real Time: Decidability and Complexity. 1-28 2004 62 Fundam. Inform. 1 http://iospress.metapress.com/openurl.asp?genre=article&issn=0169-2968&volume=62&issue=1&spage=1 db/journals/fuin/fuin62.html#HirshfeldR04