miller@cs.rochester.edu (Brad Miller) (11/15/89)
******************************************************************************
NAME/VERSION: RHET 16.54
PRESENT STATUS: Experimental (Released / Supported RESEARCH software)
[COST]: $150.
CONTACT: Peg Meeker (peg@cs.rochester.edu)
Computer Science Department
University of Rochester
Rochester, NY 14627
(Technical): Brad Miller (miller@cs.rochester.edu)
AVAILABILITY: Noncommercial; Sources included plus relevant TRs. Also
included: TIMELOGIC, TEMPOS (time reasoning subsystem)
RPRS (Plan Recognition / System Demo)
Supplied on: Symbolics Distribution format Cart Tape or
Symbolics Carry-Tape format Cart (suitable for Explorers)
1/2" 1600bpi reel TAR format.
[INTENDED USERS]: AI Programmers / researchers in KR / NL.
[DOMAIN/CATEGORY(IES)]: General KR research; NL; Planning and Plan Recognition
REPRESENTATION FORMALISMS (3 items, 6 lines):
. Frames with CONTEXTUAL equality, arbitrary constraints between
roles.
. BC / FC Horn Clauses extended with E-Unification and contextual
capabilities.
. Constraints on (typed) variables
BASE LANGUAGE: Common Lisp
OS/HARDWARE: Symbolics Genera 7.2; TI Explorer 4.1
[SYSTEM INTERFACES]: Bidirectional to Common-Lisp
[USER INTERFACES]: Symbolics style window interface
[SHORT DESCRIPTION (15 lines)]:
This is a Knowledge Representation system based on concepts
proved with HORNE. It includes 2 major modes for representing
knowledge (as Horn Clauses or as frames), which are interchangable;
a type subsystem for typed and type restricted objects (including
variables); E-unification; negation; forward and backward chaining;
complete proofs (prove, disprove, find the KB inconsistent, or
claim a goal is neither provable nor disprovable); contextual
reasoning; truth maintenance; intelligent backtracking; full LISP
compatibility (can call or be called by lisp); upward compatible with HORNE;
Allen & Koomen's TEMPOS time interval reasoning subsystem; frames have KL-1
type features, plus arbitrary predicate restrictions on slots within a frame
as well as default values for slots; separate subsystem providing
advanced user-interface facilities and ZMACS interface on the lispms.
[COMPATIBILITY]: None
[EFFICIENCY]: e-unification is very fast, though adding new equalities
(contextually) isn't.
If all you want is PROLOG, a decent PROLOG compiler will be about
100x faster than (interpreted) RHET.
[NUMBER OF INSTALLATIONS]: <5
[APPLICATIONS (3 items, 12 lines)]:
Nothing substantial; Plan Recognition system (RPRS) is sent with
RHET as a sample application.
[FURTHER DEVELOPMENTS]:
Generalization of the context trees to DAGs allowing a more complex
view of Beliefs (and other modal operators) to be implemented.
Incremental Compilation taking advantage of system's Intelligent
Backtracking.
Allowing equality to trigger forward chaining.
Goal Caching
[RELATED WORK]: HORNE / PROLOG / KL1
[REFERENCES (3 items)]:
@techreport{Rhet:UG,
Author = "Allen, James F. and Miller, Bradford W.",
Title = "The Rhetorical Knowledge Representation System: A User's
Guide",
Institution = URCS,
Number = "238 (rerevised)",
Month = Mar,
Year = 1989}
@techreport{RPRS,
Author = "Miller, Bradford W.",
Title = "The RHET Plan Recognition System",
Institution = URCS,
Number = 298,
Month = Nov,
Year = 1989}
******************************************************************************