The s(CASP) web server

Diclaimer

This is a demonstrator. This service is likely to change functionality and location. This service runs on SWI-Prolog using the [GitHub] SWI-Prolog port of s(CASP). Bugs should be reported at the issue tracker of the the GIT repository. Discussion can use the SWI-Prolog forum

About

The s(CASP) system is a top-down interpreter for ASP programs with constraints.

This work was presented at ICLP'18 (Arias et al. 2018), also available here.

And extended description of the justification trees was presented at ICLP'20 (Arias et al. 2020).

s(CASP) by Joaquin Arias, is based on s(ASP) by Kyle Marple.

s(CASP) is an implementation of the stable model semantics of constraint logic programming. Unlike similar systems, it does not employ any form of grounding. This allows s(CASP) to execute programs that are not finitely groundable, including those which make use of lists and terms.

Using as a service

The server accepts data requests on http://dev.swi-prolog.org/scasp/solve. It deals with several formats:

• POST using Content-type: text/x-scasp
  In this case the document is plain text containing both the program and the query as ?- Query. Using curl we can use this script:

          curl --data-binary @file.pl -H "Content-Type: text/x-scasp" -X POST http://dev.swi-prolog.org/scasp/solve
          

• POST using Content-type: application/json
  In this case the request is a JSON document containing these keys:
  • data
    This key is required and contains the program.
  • query
    This key is required if the program does not contain a query. If the program contains a query, the specified query in the JSON request is used, not the one in the program.
  • limit
    Max number of answers to return. Default is all.
  • format
    One of html or json. Default is json.
  • tree
    Boolean that indicates whether the justification is produced. Default true.
• POST using Content-type: application/x-www-form-urlencoded
  As above. The default reply format is html.
• GET
  Interpret the query parameters as above. The default reply format is html.