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Coursework Master’s Thesis Proposal

Coursework Master’s Thesis Proposal. December 1999 University of South Australia School of Computer and Information Science Student: David Benn Supervisor: Dan Corbett Implementing Conceptual Graph Processes. Plan. Conceptual Graphs Mineau’s Processes Implementing Processes

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Coursework Master’s Thesis Proposal

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  1. Coursework Master’s Thesis Proposal December 1999 University of South Australia School of Computer and Information Science Student: David Benn Supervisor: Dan Corbett Implementing Conceptual Graph Processes

  2. Plan • Conceptual Graphs • Mineau’s Processes • Implementing Processes • Research Issues • High-level Timeline • References David Benn, December 1999

  3. Conceptual Graphs • Sowa’s [1984] Conceptual Graphs (CGs) represent knowledge via: • Concepts • Conceptual relations (relationships between concepts) David Benn, December 1999

  4. Conceptual Graphs • Sowa’s theory provides primitives to model static knowledge. • Permits modification of knowledge base (KB) via Canonical Formation Rules, e.g. • Copy • Join • Simplify David Benn, December 1999

  5. Conceptual Graphs g1: [Feline: "]g(attr)g[Carnivore] g2: [Sitting]- (agent)g[Cat: Elsie] (location)g[Mat] Join g1 and g2 to give g3 g3: [Sitting]- (agent)g[Cat: Elsie]- (attr)g[Carnivore] (location)g[Mat] Feline Cat Tiger Lion David Benn, December 1999

  6. Processes • Dynamic updating of KB falls outside of scope of theory. • Mineau [1998] proposed processes as an extension to overcome this lack. • Need arose from a R&D project to capture knowledge about corporate processes, e.g. fabrication of windows [Gerbe´, Keller & Mineau 1998]. David Benn, December 1999

  7. Processes • Activity dependencies. • Inputs, outputs. • Precondition: before a window can be assembled, a fabrication order must have been updated with frames and panes which conform to client order. • Postconditions: when a frame is built, fabrication order is updated; likewise when a window pane is cut. From [Gerbe´, Keller & Mineau 1998] David Benn, December 1999

  8. Processes • [Gerbe´, Keller & Mineau 1998] outlined a definition of processes in terms of activities and events but said nothing about mechanism. • [Mineau 1998] introduced mechanism for processes in which: • Dynamic knowledge represented as state transitions via pre and post conditions. • Applying postconditions consists of asserting or retracting CGs in KB. David Benn, December 1999

  9. Processes • Actors and demons are specialisations of processes. • Actors take concepts and compute individuals of pre-determined concept type. • Demons take concepts and return arbitrary concept instances. • Processes take CGs as input and return arbitrary CGs. • Mineau emphasises simple process primitives which can be extended. David Benn, December 1999

  10. Processes: mechanism • A process consists of a rule set. • Each rule is a pre/post condition pair. • Process engine finds matching rule via preconditions and applies postconditions. • Process takes ≥ 1 CG parameters, yields ≥ 1 CG outputs, asserts/retracts CGs. process p (in g1...; out g2...) is David Benn, December 1999

  11. Processes: mechanism A trivial algorithm: L0: int n = 1; L1: while (n <= 10) L2: n = n + 1; [Mineau 1998] gives long partial definition for iterative factorial. Following shows example rule set. Trigger:[Line: L0]f(to_do) • Rule 0: • Pre0: • [Line: L0]f(to_do) • Post0: • [Integer: 1]f(value)f[Variable:*n] • [Line: L0]f(done) • [Line: L1]f(to_do) David Benn, December 1999

  12. Processes: mechanism Rule 1a: Pre1a: [Line: L1]f(to_do) [Boolean: True]f< ≤ >- f1-[Variable: *n] f2-[Integer: 10] Post1a: [Line: L1]f(done) [Line: L2]f(to_do) actor A trivial algorithm: L0: int n = 1; L1: while (n <= 10) L2: n = n + 1; David Benn, December 1999

  13. Processes: mechanism A trivial algorithm: L0: int n = 1; L1: while (n <= 10) L2: n = n + 1; Rule 1b: Pre1b: [Line: L1]f(to_do) [Boolean: False]f< ≤ >- f1-[Variable: *n] f2-[Integer: 10] Post1b: [Line: L1]f(done) David Benn, December 1999

  14. Processes: mechanism Rule 2: Pre2: [Line: L2]f(to_do) Post2: [Variable: *n]- (value)g[Integer: *x]- f< + >- f[Variable: *n] f[Integer: 1] [Line: L2]f(done) [Line: L1]f(to_do) A trivial algorithm: L0: int n = 1; L1: while (n <= 10) L2: n = n + 1; David Benn, December 1999

  15. Implementing Processes • “…there is only a theory which needs to be refined, implemented, and applied.” [Mineau 1999b] • Preliminary thoughts: • Need suitable way of expressing rules and processes (i.e. a process language). • Use Java for platform independence • Use Notio framework [Southey & Linders 1999] • KBs, CGs, type lattices, CFRs, CGIF/LF reading/writing • Use Mineau & Gerbe´’s [1997] contexts for rules. David Benn, December 1999

  16. Digression: Contexts • Sowa [1984] introduced PROPOSITION concept type where referent is set of CGs. • Mineau & Gerbe´ [1997] formalised contexts. • Intention constrains CGs in extension. (WoA) • Can be used to structure a KB. • Equations to extract graphs by intention, etc. • See Appendix A for overview of contexts. [Human: Fred] g(believes) g[Statement: #] intention [Entity: Earth]– (attr)g[Shape: flat] (attr)g[Location: center_of_universe] extension David Benn, December 1999

  17. Research Issues • How to represent processes • Syntactically? Algorithmically? • Can actors, demons, processes have one syntax & representation? Will latter be inefficient? (see p. 11) • Retraction mechanism • (to_do) vs (done) in algorithm example • Erasure: replacing any CG with “blank”. [Sowa 1999] • When should process engine stop? • Specify ≥ 1 rules upon which to stop? • No more matching preconditions? • Always run to completion or permit stop & restart? David Benn, December 1999

  18. Research Issues (continued) • Interaction with other systems (e.g. CharGer [Delugach 1999]): CG import, export. • Behaviour of implementation vs original conception. What has Mineau missed? • Applicability of process mechanism • [Mineau 1998] only gave factorial as example. • Needs to be demonstrated on more complex application, e.g. business processes, something more interesting? David Benn, December 1999

  19. Other Research Issues • Automatic generation of rule sets. Difficult. • Soundness and completeness • Do two postconditions conflict? • [Mineau 1999a]: constraints on processes • Conceptual Programming Environment • Logic and imperative programming. • How does current work fit in with this goal (stated in [Mineau 1998])? • Relationship to other work on dynamic CGs, dataflow languages, etc? • Higher order processes? David Benn, December 1999

  20. Timeline • Literature Review (February, March) • Scope & features (April) • Design & implement (May, June, July) • Examples (August, September) • Factorial • Business processes etc • Write thesis (October, November) David Benn, December 1999

  21. References [Delugach 1999] Delugach, H. CharGer: A Conceptual Graph Editor, [Accessed Online: December 1999], URL: http://www.cs.uah.edu/~delugach/CharGer/ [Gerbe´, Keller & Mineau 1998] Gerbe´, O., Keller, R., Mineau, G. Conceptual Graphs for Representing Business Processes in Corporate Memories. In Proceedings of the 6th International Conference on Conceptual Structures, pp. 401-415, 1998. [Mineau & Gerbe´ 1997] Mineau, G. & Gerbe´, O. Contexts: A Formal Definition of Worlds of Assertions. In Proceedings of the 5th International Conference on Conceptual Structures, pp. 80-94, 1997. [Mineau 1998] Mineau, G. From Actors to Processes: The Representation of Dynamic Knowledge Using Conceptual Graphs. In Proceedings of the 6th International Conference on Conceptual Structures, pp. 65-79, 1998. [Mineau 1999a] Mineau, G. Constraints on Processes: Essential Elements for the Validation and Execution of Processes. In Proceedings of the 7th International Conference on Conceptual Structures, pp. 66-82, 1999. David Benn, December 1999

  22. References (continued) [Mineau 1999b] Mineau, G. E-mail correspondence from Guy Mineau to David Benn, 1st December, 1999. [Southey & Linders 1999] Southey, F. & Linders, J.G., Notio — A Java API for developing CG tools. In Proceedings of the 7th International Conference on Conceptual Structures, 1999. [Sowa 1984] Sowa, J., F. Conceptual Structures: Information Processing in Mind and Machine, Addison-Wesley, 1984. [Sowa 1999] Sowa, J.F. et al, Conceptual Graph Standard, draft proposed American National Standard (dpANS) NCITS.T2/98-003, 1999. [Accessed Online: November 1999], URL: http://www.bestweb.net/~sowa/cg/cgdpansw.htm [Sowa 2000] Sowa, J., F. Knowledge Representation: Logical, Philosophical, and Computational Foundations, Brooks/Cole, 2000. David Benn, December 1999

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