Procedural Reasoning System
Encyclopedia
In Artificial Intelligence
, the Procedural Reasoning System (PRS) is a framework for constructing real-time reasoning systems that can perform complex tasks in dynamic environments. It is based on the notion of a Rational agent
or Intelligent agent
using the Belief-Desire-Intention software model.
that specifies how to do something, e.g., how to navigate down a corridor, or how to plan a path (in contrast with robotic architectures where the programmer just provides a model of what the states of the world are and how the agent's primitive actions affect them). Such a program, together with the PRS interpreter
, is used to control the agent.
The interpreter is responsible for maintaining belief
s about the world state, choosing which goals to attempt to achieve next, and choosing which knowledge area to apply in the current situation. How exactly these operations are performed might depend on domain-specific meta-level
knowledge areas. Unlike traditional AI planning systems that generate a complete plan at the beginning, and replan if unexpected things happen, PRS interleaves planning and doing actions in the world. At any point, the system might only have a partially specified plan for the future.
PRS is based on the BDI
or belief-desire-intention framework for intelligent agents. Beliefs consist of what the agent believes to be true about the current state of the world, desires consist of the agent's goals, and intentions consist of the agent's current plans for achieving those goals. Furthermore, each of these three components is typically explicitly represented somewhere within the memory of the PRS agent at runtime, which is in contrast to purely reactive systems, such as the subsumption architecture
.
at SRI International
during the 1980s. Many were involved in the development of the PRS, not limited to Michael Georgeff
, Amy L. Lansky
, and François Félix Ingrand. The framework was responsible for exploiting and popularizing the Belief-Desire-Intention model in software for control of an Intelligent agent
. The seminal application of the framework was a fault detection system for the Reaction Control System of the NASA
Space Shuttle Discovery
. Development on the PRS continued at the Australian Artificial Intelligence Institute
through to the late 1990s which lead to the development of a C++
implementation and extension called dMARS
.
The system architecture of PRS is composed of the following components:
and the Blackboard system
. The following define the general requirements for the development of the PRS:
3600 Series LISP
machine and used multiple communicating instances of PRS. The system maintained over 1000 facts about the RCS, over 650 facts for the forward RCS alone and half of which are updated continuously during the mission. A version of the PRS was used to monitor the Reaction Control System on the NASA
Space Shuttle Discovery
.
PRS was tested on Shakey the robot
including navigational and simulated jet malfunction scenarios based on the space shuttle. Later applications included a network management monitor called the Interactive Real-time Telecommunications Network Management System (IRTNMS) for Telecom Australia
.
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...
, the Procedural Reasoning System (PRS) is a framework for constructing real-time reasoning systems that can perform complex tasks in dynamic environments. It is based on the notion of a Rational agent
Rational agent
In economics, game theory, decision theory, and artificial intelligence, a rational agent is an agent which has clear preferences, models uncertainty via expected values, and always chooses to perform the action that results in the optimal outcome for itself from among all feasible actions...
or Intelligent agent
Intelligent agent
In artificial intelligence, an intelligent agent is an autonomous entity which observes through sensors and acts upon an environment using actuators and directs its activity towards achieving goals . Intelligent agents may also learn or use knowledge to achieve their goals...
using the Belief-Desire-Intention software model.
Overview
A user application is predominately defined, and provided to a PRS system is a set of knowledge areas. Each knowledge area is a piece of procedural knowledgeProcedural knowledge
Procedural knowledge, also known as imperative knowledge, is the knowledge exercised in the performance of some task. See below for the specific meaning of this term in cognitive psychology and intellectual property law....
that specifies how to do something, e.g., how to navigate down a corridor, or how to plan a path (in contrast with robotic architectures where the programmer just provides a model of what the states of the world are and how the agent's primitive actions affect them). Such a program, together with the PRS interpreter
Interpreter (computing)
In computer science, an interpreter normally means a computer program that executes, i.e. performs, instructions written in a programming language...
, is used to control the agent.
The interpreter is responsible for maintaining belief
Belief
Belief is the psychological state in which an individual holds a proposition or premise to be true.-Belief, knowledge and epistemology:The terms belief and knowledge are used differently in philosophy....
s about the world state, choosing which goals to attempt to achieve next, and choosing which knowledge area to apply in the current situation. How exactly these operations are performed might depend on domain-specific meta-level
Metaknowledge
Metaknowledge or meta-knowledge is knowledge about a preselected knowledge.For the reason of different definitions of knowledge in the subject matter literature, meta-information is or is not included in meta-knowledge. Detailed cognitive, systemic and epistemic study of human knowledge requires a...
knowledge areas. Unlike traditional AI planning systems that generate a complete plan at the beginning, and replan if unexpected things happen, PRS interleaves planning and doing actions in the world. At any point, the system might only have a partially specified plan for the future.
PRS is based on the BDI
BDI software agent
The Belief-Desire-Intention software model is a software model developed for programming intelligent agents. Superficially characterized by the implementation of an agent's beliefs, desires and intentions, it actually uses these concepts to solve a particular problem in agent programming...
or belief-desire-intention framework for intelligent agents. Beliefs consist of what the agent believes to be true about the current state of the world, desires consist of the agent's goals, and intentions consist of the agent's current plans for achieving those goals. Furthermore, each of these three components is typically explicitly represented somewhere within the memory of the PRS agent at runtime, which is in contrast to purely reactive systems, such as the subsumption architecture
Subsumption architecture
Subsumption architecture is a reactive robot architecture heavily associated with behavior-based robotics. The term was introduced by Rodney Brooks and colleagues in 1986...
.
History
The PRS was developed by the Artificial Intelligence CenterArtificial Intelligence Center
The Artificial Intelligence Center at SRI International was founded in 1966 by Charles Rosen and studies artificial intelligence. One of their early projects was Shakey the Robot, the first general-purpose mobile robot. More recently, the center funded early development of CALO and Siri....
at SRI International
SRI International
SRI International , founded as Stanford Research Institute, is one of the world's largest contract research institutes. Based in Menlo Park, California, the trustees of Stanford University established it in 1946 as a center of innovation to support economic development in the region. It was later...
during the 1980s. Many were involved in the development of the PRS, not limited to Michael Georgeff
Michael Georgeff
Michael Peter Georgeff is a computer scientist and entrepreneur who has made contributions in the areas of Intelligent Software Agents and eHealth.- Overview :...
, Amy L. Lansky
Amy L. Lansky
Amy L. Lansky , is an American author, computer scientist, and homeopath, noted for having written Impossible Cure: the Promise of Homeopathy.-Life:...
, and François Félix Ingrand. The framework was responsible for exploiting and popularizing the Belief-Desire-Intention model in software for control of an Intelligent agent
Intelligent agent
In artificial intelligence, an intelligent agent is an autonomous entity which observes through sensors and acts upon an environment using actuators and directs its activity towards achieving goals . Intelligent agents may also learn or use knowledge to achieve their goals...
. The seminal application of the framework was a fault detection system for the Reaction Control System of the NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
Space Shuttle Discovery
Space Shuttle Discovery
Space Shuttle Discovery is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States, and was operational from its maiden flight, STS-41-D on August 30, 1984, until its final landing during STS-133 on March 9, 2011...
. Development on the PRS continued at the Australian Artificial Intelligence Institute
Australian Artificial Intelligence Institute
In Australia, the Australian Artificial Intelligence Institute was a government funded research and development laboratory for investigating and commercializing Artificial Intelligence, specifically Intelligent Software Agents.- History :The AAII was started in 1988 as an initiative by the Hawke...
through to the late 1990s which lead to the development of a C++
C++
C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...
implementation and extension called dMARS
Distributed Multi-Agent Reasoning System
In artificial intelligence, the Distributed Multi-Agent Reasoning System is a platform for intelligent software agents developed at the AAII that makes uses of the BDI software model. The design for dMARS is an extension of the intelligent agent cognitive architecture developed at SRI...
.
Architecture
- Database for beliefs about the world, represented using first order predicate calculus.
- Goals to be realized by the system as conditions over an interval of time on internal and external state descriptions (desires).
- Knowledge Areas (KA) or plans that define sequences of low-level actions toward achieving a goal in specific situations.
- Intentions that include those KA that have been selected for current and eventual execution.
- Interpreter or inference mechanism that manages the system.
Features
The PRS was developed for embedded application in dynamic and real-time environments. As such it specifically addressed the limitations of other contemporary control and reasoning architectures like Expert SystemsExpert 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...
and the Blackboard system
Blackboard system
A blackboard system is an artificial intelligence application based on the blackboard architectural model, where a common knowledge base, the "blackboard", is iteratively updated by a diverse group of specialist knowledge sources, starting with a problem specification and ending with a solution...
. The following define the general requirements for the development of the PRS:
- asynchronous event handling
- guaranteed reaction and response types
- procedural representation of knowledge
- handling of multiple problems
- reactive and goal-directed behavior
- focus of attention
- reflective reasoning capabilities
- continuous embedded operation
- handling of incomplete of inaccurate data
- handling of transients
- modeling delayed feedback
- operator control
Applications
The seminal application of the PRS was a monitoring and fault detection system for the Reaction Control System (RCS) on the NASA space shuttle. The RCS provides propulsive forces from a collection of jet thrusters and controls attitude of the space shuttle. A PRS-based fault diagnostic system was developed and tested using a simulator. It included over 100 KAs and over 25 meta level KAs. RCS specific KAs were written by space shuttle mission controllers. It was implemented on the SymbolicsSymbolics
Symbolics refers to two companies: now-defunct computer manufacturer Symbolics, Inc., and a privately held company that acquired the assets of the former company and continues to sell and maintain the Open Genera Lisp system and the Macsyma computer algebra system.The symbolics.com domain was...
3600 Series LISP
Lisp
A lisp is a speech impediment, historically also known as sigmatism. Stereotypically, people with a lisp are unable to pronounce sibilants , and replace them with interdentals , though there are actually several kinds of lisp...
machine and used multiple communicating instances of PRS. The system maintained over 1000 facts about the RCS, over 650 facts for the forward RCS alone and half of which are updated continuously during the mission. A version of the PRS was used to monitor the Reaction Control System on the NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
Space Shuttle Discovery
Space Shuttle Discovery
Space Shuttle Discovery is one of the retired orbiters of the Space Shuttle program of NASA, the space agency of the United States, and was operational from its maiden flight, STS-41-D on August 30, 1984, until its final landing during STS-133 on March 9, 2011...
.
PRS was tested on Shakey the robot
Shakey the Robot
Shakey the Robot was the first general-purpose mobile robot to be able to reason about its own actions. While other robots would have to be instructed on each individual step of completing a larger task, Shakey could analyze the command and break it down into basic chunks by itself...
including navigational and simulated jet malfunction scenarios based on the space shuttle. Later applications included a network management monitor called the Interactive Real-time Telecommunications Network Management System (IRTNMS) for Telecom Australia
Telecom Australia
Telecom Australia was the trading name of the:* Australian Telecommunications Commission * Australian Telecommunications Corporation * Australian and Overseas Telecommunications Corporation...
.
Extensions
The following list the major implementations and extensions of the PRS architecture.- UM-PRS http://www.marcush.net/IRS/irs_downloads.html
- OpenPRS (formerly C-PRS and Propice) http://www.laas.fr/~felix/PRS https://softs.laas.fr/openrobots/wiki/openprs
- AgentSpeakAgentSpeakAgentSpeak is an agent-oriented programming language. It is based on logic programming and the BDI architecture for autonomous agents...
- Distributed Multi-Agent Reasoning SystemDistributed Multi-Agent Reasoning SystemIn artificial intelligence, the Distributed Multi-Agent Reasoning System is a platform for intelligent software agents developed at the AAII that makes uses of the BDI software model. The design for dMARS is an extension of the intelligent agent cognitive architecture developed at SRI...
(dMARS) - JAM http://www.marcush.net/IRS/irs_downloads.html
- JACK Intelligent AgentsJACK Intelligent AgentsJACK Intelligent Agents or JACK is a framework in Java for multi-agent system development. JACK Intelligent Agents was built by Agent Oriented Software Pty. Ltd. and is a third generation agent platform building on the experiences of the Procedural Reasoning System and Distributed Multi-Agent...
- SRI Procedural Agent Realization Kit (SPARK) http://www.ai.sri.com/~spark/
- PRS-CL http://www.ai.sri.com/~prs/
See also
- Distributed Multi-Agent Reasoning SystemDistributed Multi-Agent Reasoning SystemIn artificial intelligence, the Distributed Multi-Agent Reasoning System is a platform for intelligent software agents developed at the AAII that makes uses of the BDI software model. The design for dMARS is an extension of the intelligent agent cognitive architecture developed at SRI...
- JACK Intelligent AgentsJACK Intelligent AgentsJACK Intelligent Agents or JACK is a framework in Java for multi-agent system development. JACK Intelligent Agents was built by Agent Oriented Software Pty. Ltd. and is a third generation agent platform building on the experiences of the Procedural Reasoning System and Distributed Multi-Agent...
- Belief-Desire-Intention software model
- Intelligent agentIntelligent agentIn artificial intelligence, an intelligent agent is an autonomous entity which observes through sensors and acts upon an environment using actuators and directs its activity towards achieving goals . Intelligent agents may also learn or use knowledge to achieve their goals...
External links
- PRS-CL: A Procedural Reasoning System An extension to PRS maintained by SRI International