Decidability properties for fragments of CHR

作     者：Gabbrielli, Maurizio Mauro, Jacopo Meo, Maria Chiara Sneyers, Jon 

作者机构：Univ Bologna Dipartimento Sci Informaz I-40126 Bologna Italy Univ Bologna Lab Focus INRIA I-40126 Bologna Italy Univ G dAnnunzio Dipartimento Sci Pescara Italy Katholieke Univ Leuven Dept Comp Wetenschappen Louvain Belgium 

出 版 物：《THEORY AND PRACTICE OF LOGIC PROGRAMMING》 

年 卷 期：2010年第10卷第4-6期

页      面：611-626页

核心收录：

学科分类：08[工学] 0835[工学-软件工程] 0701[理学-数学] 0812[工学-计算机科学与技术（可授工学、理学学位）] 

主　　题：constraint programming expressivity well-structured transition systems 

摘      要：We study the decidability of termination for two CH R dialects which, similarly to the Datalog like languages, are defined by using a signature which does not allow function symbols (of arity 0). Both languages allow the use of the = built-in in the body of rules, thus are built on a host language that supports unification. However each imposes one further restriction. The first CHR dialect allows only range-restricted rules, that is, it does not allow the use of variables in the body or in the guard of a rule if they do not appear in the head. We show that the existence of an infinite computation is decidable for this dialect. The second dialect instead limits the number of atoms in the head of rules to one. We prove that in this case, the existence of a terminating computation is decidable. These results show that both dialects are strictly less expressive(1) than Turing Machines. It is worth noting that the language (without function symbols) without these restrictions is as expressive as Turing Machines.