Under consideration for publication in Theory and Practice of Logic Programming 1 XSB: Extending Prolog with Tabled Logic Programming TERRANCE SWIFT CENTRIA, Faculdade de Ciˆencias e Tecnologia Univ. Nova de Lisboa, 2825-516 Caparica, Portugal (e-mail:
[email protected]) DAVID S. WARREN Computer Science Department, SUNY Stony Brook Stony Brook, New York, USA (e-mail:
[email protected]) submitted 4th October 2009; revised 28th February 2010; accepted 22nd November 2010 Abstract The paradigm of Tabled Logic Programming (TLP) is now supported by a number of Pro- log systems, including XSB, YAP Prolog, B-Prolog, Mercury, ALS, and Ciao. The reasons for this are partly theoretical: tabling ensures termination and optimal known complex- ity for queries to a large class of programs. However the overriding reasons are practical. TLP allows sophisticated programs to be written concisely and efficiently, especially when mechanisms such as tabled negation and call and answer subsumption are supported. As a result TLP has now been used in a variety of applications from program analysis to querying over the semantic web. This paper provides a survey of TLP and its applications as implemented in XSB Prolog, along with discussion of how XSB supports tabling with dynamically changing code, and in a multi-threaded environment 1. KEYWORDS: Prolog, Tabling, Implementation, Non-monotonic Reasoning arXiv:1012.5123v1 [cs.PL] 23 Dec 2010 1 Introduction Since its inception, a primary goal of XSB has been to expand the areas in which Prolog is used, by making Prolog more powerful, more efficient, and more declar- ative. In 1993 when XSB was first released, it supported this goal by including both tabled resolution for definite programs, which provided it with deductive database-style features of such systems as Coral (Ramakrishnan et al.