OPS5
Encyclopedia
OPS5 is a rule-based or production system
computer language, notable as the first such language to be used in a successful expert system
, the R1/XCON system used to configure VAX
computers.
The OPS (said to be short for "Official Production System") family was developed in the late 1970s
by Charles Forgy
while at Carnegie Mellon University
. Allen Newell
's research group in artificial intelligence
had been working on production systems for some time, but Forgy's implementation, based on his Rete algorithm
, was especially efficient, sufficiently so that it was possible to scale up to larger problems involving hundreds or thousands of rules.
OPS5 uses a forward chaining
inference engine
; programs execute by scanning "working memory elements" (which are vaguely object-like, with classes and attributes) looking for matches with the rules in "production memory". Rules have actions that may modify or remove the matched element, create new ones, perform side effects such as output, and so forth. Execution continues until no more matches can be found.
OPS4 was an early version, while OPS83 came later.
The first implementation of OPS5 was written in Lisp
, and later rewritten in BLISS for speed.
DEC OPS5 is an extended implementation of the OPS5 language definition, developed for use with the VMS, RISC ULTRIX, and DEC OSF/1 operating systems.
Production system
A production system is a computer program typically used to provide some form of artificial intelligence, which consists primarily of a set of rules about behavior. These rules, termed productions, are a basic representation found useful in automated planning, expert systems and action selection...
computer language, notable as the first such language to be used in a successful expert system
Expert system
In artificial intelligence, an expert system is a computer system that emulates the decision-making ability of a human expert. Expert systems are designed to solve complex problems by reasoning about knowledge, like an expert, and not by following the procedure of a developer as is the case in...
, the R1/XCON system used to configure VAX
VAX
VAX was an instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. A 32-bit complex instruction set computer ISA, it was designed to extend or replace DEC's various Programmed Data Processor ISAs...
computers.
The OPS (said to be short for "Official Production System") family was developed in the late 1970s
1970s
File:1970s decade montage.png|From left, clockwise: US President Richard Nixon doing the V for Victory sign after his resignation from office after the Watergate scandal in 1974; Refugees aboard a US naval boat after the Fall of Saigon, leading to the end of the Vietnam War in 1975; The 1973 oil...
by Charles Forgy
Charles Forgy
Dr Charles L. Forgy is a computer scientist, known for developing the Rete algorithm used in his OPS5 and other production system languages used to build expert systems.- Early Life :Dr...
while at Carnegie Mellon University
Carnegie Mellon University
Carnegie Mellon University is a private research university in Pittsburgh, Pennsylvania, United States....
. Allen Newell
Allen Newell
Allen Newell was a researcher in computer science and cognitive psychology at the RAND corporation and at Carnegie Mellon University’s School of Computer Science, Tepper School of Business, and Department of Psychology...
's research group in artificial intelligence
Artificial intelligence
Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...
had been working on production systems for some time, but Forgy's implementation, based on his Rete algorithm
Rete algorithm
The Rete algorithm is an efficient pattern matching algorithm for implementing production rule systems. The Rete algorithm was designed by Dr Charles L. Forgy of Carnegie Mellon University, first published in a working paper in 1974, and later elaborated in his 1979 Ph.D. thesis and a 1982 paper...
, was especially efficient, sufficiently so that it was possible to scale up to larger problems involving hundreds or thousands of rules.
OPS5 uses a forward chaining
Forward chaining
Forward chaining is one of the two main methods of reasoning when using inference rules and can be described logically as repeated application of modus ponens. Forward chaining is a popular implementation strategy for expert systems, business and production rule systems...
inference engine
Inference engine
In computer science, and specifically the branches of knowledge engineering and artificial intelligence, an inference engine is a computer program that tries to derive answers from a knowledge base. It is the "brain" that expert systems use to reason about the information in the knowledge base for...
; programs execute by scanning "working memory elements" (which are vaguely object-like, with classes and attributes) looking for matches with the rules in "production memory". Rules have actions that may modify or remove the matched element, create new ones, perform side effects such as output, and so forth. Execution continues until no more matches can be found.
OPS4 was an early version, while OPS83 came later.
The first implementation of OPS5 was written in Lisp
Lisp programming language
Lisp is a family of computer programming languages with a long history and a distinctive, fully parenthesized syntax. Originally specified in 1958, Lisp is the second-oldest high-level programming language in widespread use today; only Fortran is older...
, and later rewritten in BLISS for speed.
DEC OPS5 is an extended implementation of the OPS5 language definition, developed for use with the VMS, RISC ULTRIX, and DEC OSF/1 operating systems.
External links
- Free OPS5 compiler
- OPS5 overview
- OPS5 Reference manual
- RuleWorks - Language based on OPS5
- OPS5: RETE-based expert system shell - CMU Artificial Intelligence Repository