Dissertations in Logic Programming

An Open Invitation:
The column on dissertations in Logic Programming is aimed at widely publicizing recent dissertations (and even MS Theses) deadling with topics relevant to Logic Programming. This is an outstanding opportunity to
  • Shine a spotlight on the new generation of logic programmers
  • Demonstrate that the field of logic programming is alive with new "blood" 
  • Provide to our graduating students with an additional opportunity to get themselves known to the logic programming community at large
  • Perhaps facilitate the creation of contacts with potential employers
Please, if you are a student who is about to complete a Thesis or Dissertation in logic programming, if you are a faculty member who is advising a student completing a Thesis in logic programming, if you have a friend/colleague/relative/... who meets such requirements, please send me a message and help me advertising these fantastic achievements.

    Enrico
  

Efficient Parallel Execution of Answer Set Programs

Hung Viet Le
New Mexico State University
June 2007

Logic-based and non-monotonic reasoning systems (LPNMRs) have grown in popularity over the last few years, as they provide formal and executable frameworks to describe the capabilities of intelligent software agents and to reason about them. 

In spite of the fantastic efforts in developing efficient implementations, there are important application domains that are beyond the computational reach of existing sequential systems. In this research, we explore the use of parallelism as an avenue to expand efficiency and applicability of LPNMR systems. We explore the major issues involved in the automatic exploitation of parallelism from the execution models of LPNMR systems. We describe orthogonal techniques to parallelize the computational models of Answer Set Programming, and investigate a wide range of  sharing strategies and dynamic schedulers. We demonstrate the effectiveness of the proposed techniques in a prototype implementation.


Towards A Programming Environment For Answer Set Programming


Omar El-Khatib
 New Mexico State University
 June 2007

We present a system, called ASP-PROLOG, which provides a tight and well-defined integration of Prolog and Answer Set Programming (ASP). The combined system  enhances the expressive power of ASP, allowing us to write programs that  reason about dynamic ASP modules and about collections of answer sets. These features are vital in a number of application domains (e.g., planning, scheduling, diagnosis).
We describe the design of ASP-PROLOG along with its  implementation, realized using CIAO Prolog and Smodels. 

In addition, we  introduce the notion of off-line justification for Answer Set Programming. Justifications provide a graph-based explanation of the truth value of  an atom w.r.t. a given answer set. The notion of justification accounts for the specifics of answer set semantics. The thesis extends also this notion to  provide justification of atoms during the computation of an answer set  (on-line justification), and presents an integration of on-line justifications  within the computation model of Smodels. Off-line and on-line justifications provide  useful tools to enhance understanding of ASP, and they offer a basic data structure to support methodologies and tools for debugging answer set programs. An implementation has been developed in ASP-PROLOG.

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