Disjunctive Answer Set Solvers via Templates

Answer set programming is a declarative programming paradigm oriented towards difficult combinatorial search problems. A fundamental task in answer set programming is to compute stable models, i.e., solutions of logic programs. Answer set solvers are the programs that perform this task. The problem of deciding whether a disjunctive program has a stable model is $\Sigma^P_2$-complete. The high complexity of reasoning within disjunctive logic programming is responsible for few solvers capable of dealing with such programs, namely DLV, GnT, Cmodels, CLASP and WASP. In this paper we show that transition systems introduced by Nieuwenhuis, Oliveras, and Tinelli to model and analyze satisfiability solvers can be adapted for disjunctive answer set solvers. Transition systems give a unifying perspective and bring clarity in the description and comparison of solvers. They can be effectively used for analyzing, comparing and proving correctness of search algorithms as well as inspiring new ideas in the design of disjunctive answer set solvers. In this light, we introduce a general template, which accounts for major techniques implemented in disjunctive solvers. We then illustrate how this general template captures solvers DLV, GnT and Cmodels. We also show how this framework provides a convenient tool for designing new solving algorithms by means of combinations of techniques employed in different solvers.Comment: To appear in Theory and Practice of Logic Programming (TPLP

Healthy Relationships, Employment, and Reentry

This brief will provide an overview of the evidence supporting the interrelatedness of employment, healthy relationships, family well-being, and recidivism. It will also give the perspectives of expert program practitioners who are successfully integrating programming related to employment, prison reentry, healthy relationships, and responsible fatherhood. Finally, this brief will offer program and policy recommendations for leveraging the positive impacts of healthy relationships on employment and reentry and vice versa

Parents and Children Together: Design and Implementation of Two Healthy Marriage Programs

The Parents and Children Together (PACT) evaluation, conducted by Mathematica Policy Research for the Office of Research, Planning, and Evaluation, Administration for Children and Families (ACF), U.S. Department of Health and Human Services, is examining a set of Healthy Marriage (HM) and Responsible Fatherhood (RF) grantees funded by ACF's Office of Family Assistance (OFA) in 2011. Recognizing that grantees' programs continue to grow and develop, the PACT evaluation aims to provide foundational information to guide ongoing and future program design and evaluation efforts, and to build the evidence base for programming

Analysis of high-order languages for use on space station application software

Considered in this study is the general and not easily resolved problem of how to choose the right programming language for a particular task. This is specialized to the question of which versions of what languages should be chosen for the multitude of tasks that the Marshall Space Flight Center will be responsible for in the Space Station. Four criteria are presented: theoretical considerations, quantitative matrices, qualitative benchmarks, and the monitoring of programmers. Specific recommendations for future studies are given to resolve these questions for the Space Station

Software Implemented Fault-Tolerant (SIFT) user's guide

Program development for a Software Implemented Fault Tolerant (SIFT) computer system is accomplished in the NASA LaRC AIRLAB facility using a DEC VAX-11 to interface with eight Bendix BDX 930 flight control processors. The interface software which provides this SIFT program development capability was developed by AIRLAB personnel. This technical memorandum describes the application and design of this software in detail, and is intended to assist both the user in performance of SIFT research and the systems programmer responsible for maintaining and/or upgrading the SIFT programming environment