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From: miller@cs.rochester.edu (Brad Miller)
Newsgroups: comp.ai.shells
Subject: Survey of ES Shells: RHET 16.54
Message-ID: <7330@uklirb.UUCP>
Date: 14 Nov 89 18:21:00 GMT
References: <7315@uklirb.UUCP>
Sender: shell@uklirb.UUCP
Reply-To: miller@cs.rochester.edu
Organization: University of Rochester, Department of Computer Science
Lines: 78
Approved: shell@uklirb.uucp
Posted-Date: Wed Nov 15 12:06:06 GMT 1989
Postal-Address: 610 CS Building, Comp Sci Dept., U. Rochester, Rochester NY 14627
Phone: 716-275-1118

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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}

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