WO1988005195A1 - Organisation de systemes a base theorique - Google Patents

Organisation de systemes a base theorique Download PDF

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Publication number
WO1988005195A1
WO1988005195A1 PCT/GB1988/000005 GB8800005W WO8805195A1 WO 1988005195 A1 WO1988005195 A1 WO 1988005195A1 GB 8800005 W GB8800005 W GB 8800005W WO 8805195 A1 WO8805195 A1 WO 8805195A1
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WO
WIPO (PCT)
Prior art keywords
theory
theories
interpreter
relationships
assimilator
Prior art date
Application number
PCT/GB1988/000005
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English (en)
Inventor
Damian Sean Black
John Cyril Manley
Original Assignee
Hewlett-Packard Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hewlett-Packard Limited filed Critical Hewlett-Packard Limited
Publication of WO1988005195A1 publication Critical patent/WO1988005195A1/fr

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Classifications

    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
    • G06N5/00—Computing arrangements using knowledge-based models
    • G06N5/02—Knowledge representation; Symbolic representation

Definitions

  • the present specification also assumes a basic knowledge of logic programming such as that possessed by any skilled worker in the field.
  • Prolog is assumed (for a basic text, refer to "Programming in Prolog", W. F. Clocksin and C. S. Mellish, Springer-Verlag, 1984).
  • the basic concepts of a knowledge-base management system are also assumed (see Proc First Int Conf on Expert Database Systems, cited above).
  • Previous approaches to theory-based systems have used fixed, built-in schemes for defining the relationship between theory names, theories and their interpreters and assimilators.
  • assimilator and attributes are contained in a single metatheory with a built-in link to that theory.
  • genealogy theory 19 which is primarily composed of a set of rules defining complex genealogical relationships, such as ancestorhood and cousinhood, and many of which are therefore recursive.
  • This theory has a special interpreter theory 19, which is designed to deal efficiently with recursive rules and so contain the types of inference explosion that can otherwise arise with such rules.
  • the genealogy theory itself draws on the simple personal relationship information contained in the employment theory 10 - another, and different, example of theory-to-theory linkage.
  • every theory (including the metatheory interpreters, assimilators, and attribute theories) has an assimilator metatheory and an attribute metatheory; so, correspondingly, there are chains of assimilator theories and attribute theories, which are terminated by a built-in assimilator which merely adds or deletes any item specified, and a trivial built-in attribute theory which is the empty theory.
  • system theory 22 This is the theory that details all the theories in the system, including itself, and the relationships between them (preferably holding these relationships as a set of four-term relationships each relating a theory with an attribute theory, an assimilator theory, and an interpreter theory).
  • theory to theory name There are four types of relationship that appear in the system theory: theory to theory name, and three corresponding to the relationships described above (theory name to interpreter name; theory name to assimilator name; and theory name to attribute theory name).
  • the system theory cannot be adequately represented in the drawing, because while it exists as a distinct theory, it also contains all the other theories and indeed itself.
  • the system theory holds a relationship statement between that theory and other theories associated with it; that is, all relationships between theories are explicitly represented in the form of a set of logical statements by the system theory. It is convenient for the relationship statement to define various distinct forms of association orrelationship, so that the types of relationship of a theory to other theories are automatically determined; in other words, there are distinct types of relationship between a theory and an interpreter theory, an assimilator theory, and an attribute theory. It will however be realised that differences between the various types of relationship are only defined by the structure of the system itself to the extent that each type of relationship has a specific place (first, second, etc) in the relationship statement.
  • the manner in which the relationships between the various theories are held in the present system allows the relationships between the theories, and the population of theories, to change with time. For example, it may be desired to investigate the effects of various changes of exchange rate.
  • a financial theory (not shown) may be constructed which defines the manner in which discounts are determined.
  • a series of queries may be directed to this financial theory, and these may cause the setting up of a series of distinct discount theories (not shown), one for each possible exchange rate being considered.
  • the system theory operates to keep track of these different discount theories, which are of course mutually inconsistent. (A simpler example is when a theory is updated; the system then includes the old theory and the new (updated) one).
  • the system then exists in a considerable number of distinct versions, corresponding to the different possible exchange rates being considered or to successive periods of time, and the appropriate version has to be selected for any particular query.
  • metatheory which extends the logical update primitives provided by the underlying knowledge based management system to enforce syntactic and semantic constraints, on updates of the object theory.
  • attribute metatheory which expresses characteristics of the object theory clauses, such as type constraints, used by interpreters and assimilators to control inference and updating.
  • interpreters and assimilators are themselves theories, they also may be associated with metatheories. However, only one or two levels of interpretation will be used in practice, for reasons of efficiency. Recursion is terminated by special built-in interpreter and assimilation theories.
  • the whole knowledge base is represented by a special theory, the system theory, which is distinguished only by its role.
  • This system theory describes the relationship between the name of a theory, the theory itself, and the names of its metatheories. In defining this relationship, the full power of Horn clause logic can be brought to bear.
  • a named object theory can have many interpreters and a particular interpreter may be used on many object theories.
  • the ability to represent many-to-many relationships between theories and their metatheories allows reasoning within the system about which metatheory is appropriate for a particular task. This contrasts with the fixed associations of a static amalgamation. Since the system is itself a theory, it can easily be extended by including extra axios to define, for example, a variety of methods for retrieving named theories and choosing any metatheories required.
  • a query is made in a named theory, that theory must be retrieved from the system. This is achieved by querying the system, by means of a predicate interface which is standard for all theories.
  • This interface operates in the underlying knowledge based management system (KBMS), and takes a theory name and a set of goals: kbms_prove (System, TheoryName, Goals).
  • KBMS knowledge based management system
  • the system theory is consulted to find the current version of the named theory and the name of its interpreter. If there is more than one interpreter for the named theory, then inference within the system is used to choose between them.
  • the KBMS attempts to prove that the interpreter can solve the goals. (If an interpreter is required for the interpreter, recursion occurs until the built-in interpreter is reached).
  • interpreters specific to individual theories increases the efficiency of proving goals, since the proof techniques can be matched to the specific domains of the various theories, using appropriate syntactic and semantic constraints in inference control.
  • each assimilator must understand, and be able to translate into, the representation of the theory it is updating.
  • An update is specified as a list of actions - all actions are eventually reduced to primitive declarative add and delete operations on the theory being updated.
  • the simplest form of assimilator simply carries out such additions and deletions.
  • a more elaborate assimilator will carry out some form of checking for consistency, either clause by clause as they are added (with provision for ignoring unavoidably inconsistent states of the theory during updating) or on the theory as fully updated; in either case, there is provision for backtracking and restoration of the original state of the theory in the event of an attempted illegal update.
  • the abstraction of consistency checking from a theory into an assimilator theory makes it more likely that an assimilator theory will be applicable to more than one theory.
  • the system theory in effect contains all theories, since it contains a description of all relationships between theories and any theory can be reached by means of a query directed initially to the system theory to find the required theory.
  • An update to a theory is therefore also an update to the system, and since the system itself is a theory, a new system (or system theory) is created every time an update occurs. All previous versions of the system remain available as long as they are referenced.
  • the system itself also has its own assimilator.
  • a typical task for the system assimilator might be to check that when a new theory is being added to the system, all of its nominated metatheories also belong to the system.
  • the invention can be implemented by means of a Prolog program fragment implementing this facility.
  • a program with statements in first-order logic thus forms a detailed embodiment of the invention. (The implementation of theories within Prolog is straightforward and not described here).
  • the following description is in the form of a particular predicate theory (the system theory) which relates theory names to theories to interpreter names, assimilator names and attribute names.
  • the system theory is a 5-place predicate theory relating a theory name TheoryName with a theory Theons, an interpreter theory name IntName, an assimilator theory name AssName and an attribute theory name AttrName.
  • IntName names a theory defining a provability relation for Theory.
  • AssName names a theory defining an updatability relation for Theory.
  • AttrName is the name of the theory which holds description information about (attributes of) Theory.
  • a formal definition in first-order logic of the meaning of "prove” and "update” is as follows. Clauses defining the conditions under which particular associations apply are represented within the system theory. The system theory is used during the first stage of query and update handling, and specified in the third (prove) and fifth (update) predicates . prove (System, system, Goals) :- iaterpretTheary (System , Goals). prove (System, prolog Int, interpret(ThearyName,Theory,AttrName,Goals) :- in terpretTheory (Theory, Goals).

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  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Computing Systems (AREA)
  • Data Mining & Analysis (AREA)
  • Evolutionary Computation (AREA)
  • Physics & Mathematics (AREA)
  • Computational Linguistics (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Software Systems (AREA)
  • Artificial Intelligence (AREA)
  • Devices For Executing Special Programs (AREA)
  • Stored Programmes (AREA)

Abstract

Un système à base théorique et spécialement un système de programmation logique (système de gestion à base de connaissances, KBMS) comprend diverses théories - emploi (10), généalogie (18), données sur les pièces (11), escompte et planification financière - certaines d'entre elles se référant les unes aux autres (par exemple la théorie de l'escompte se réfère à la théorie des données sur les pièces (11)). Certaines ont des programmes d'interprètation spéciaux (par exemple la théorie des tables (16) pour la théorie des données sur les pièces (11)); certaines peuvent avoir des théories d'assimilations spéciales (programmes mis à jour) (par exemple (14) pour la théorie (10)) et/ou des théories d'attributs (15). Une théorie de système (22) contient ou représente la relation entre les théories à l'intérieur du système, leurs noms, leurs programmes d'interprétation et d'assimilation et commande l'accès aux autres théories. En tant que théorie, la théorie du système elle-même peut être conservée de la même façon que n'importe quelle autre, en étant mise à jour pour permettre la création de nouvelles théories (par exemple par mise à jour).
PCT/GB1988/000005 1987-01-06 1988-01-06 Organisation de systemes a base theorique WO1988005195A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8700188 1987-01-06
GB878700188A GB8700188D0 (en) 1987-01-06 1987-01-06 Organisation of theory-based systems

Publications (1)

Publication Number Publication Date
WO1988005195A1 true WO1988005195A1 (fr) 1988-07-14

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PCT/GB1988/000005 WO1988005195A1 (fr) 1987-01-06 1988-01-06 Organisation de systemes a base theorique

Country Status (4)

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EP (1) EP0296216A1 (fr)
JP (1) JPH01502784A (fr)
GB (1) GB8700188D0 (fr)
WO (1) WO1988005195A1 (fr)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1986000156A1 (fr) * 1984-06-07 1986-01-03 Teknowledge, Inc. Outil pour systemes de connaissances

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1986000156A1 (fr) * 1984-06-07 1986-01-03 Teknowledge, Inc. Outil pour systemes de connaissances

Also Published As

Publication number Publication date
EP0296216A1 (fr) 1988-12-28
GB8700188D0 (en) 1987-02-11
JPH01502784A (ja) 1989-09-21

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