Coursework Master

1
Coursework Masters 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
• Mineaus Processes
• Implementing Processes
• Research Issues
• High-level Timeline
• References

3
Conceptual Graphs

• Sowas 1984 Conceptual Graphs (CGs) represent
  knowledge via
• Concepts
• Conceptual relations (relationships between
  concepts)

4
Conceptual Graphs

• Sowas theory provides primitives to model static
  knowledge.
• Permits modification of knowledge base (KB) via
  Canonical Formation Rules, e.g.
• Copy
• Join
• Simplify

5
Conceptual Graphs
g1 Feline "g(attr)gCarnivore g2
Sitting- (agent)gCat Elsie
(location)gMat Join g1 and g2 to give g3 g3
Sitting- (agent)gCat Elsie-
(attr)gCarnivore (location)gMat
Feline
Cat Tiger Lion
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 RD project to capture
  knowledge about corporate processes, e.g.
  fabrication of windows Gerbe, Keller Mineau
  1998.

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
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.

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.

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

11
Processes mechanism

• A trivial algorithm
• L0 int n 1
• L1 while (n lt 10)
• L2 n n 1

Mineau 1998 gives long partial definition for
iterative factorial. Following shows example
rule set.
Trigger Line L0f(to_do)
Rule 0 Pre0 Line L0f(to_do) Post0 Integer
1f(value)fVariablen Line
L0f(done) Line L1f(to_do)
12
Processes mechanism

• Rule 1a
• Pre1a
• Line L1f(to_do)
• Boolean Trueflt gt-
• f1-Variable n
• f2-Integer 10
• Post1a
• Line L1f(done)
• Line L2f(to_do)

actor
A trivial algorithm L0 int n 1 L1 while (n
lt 10) L2 n n 1
13
Processes mechanism
A trivial algorithm L0 int n 1 L1 while (n
lt 10) L2 n n 1

• Rule 1b
• Pre1b
• Line L1f(to_do)
• Boolean Falseflt gt-
• f1-Variable n
• f2-Integer 10
• Post1b
• Line L1f(done)

14
Processes mechanism

• Rule 2
• Pre2
• Line L2f(to_do)
• Post2
• Variable n-
• (value)gInteger x-
• flt gt-
• fVariable n
• fInteger 1
• Line L2f(done)
• Line L1f(to_do)

A trivial algorithm L0 int n 1 L1 while (n
lt 10) L2 n n 1
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 Gerbes 1997 contexts for rules.

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) gStatement
intention
Entity Earth (attr)gShape
flat (attr)gLocation center_of_universe
extension
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?

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?

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?

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)

21
References

• Delugach 1999 Delugach, H. CharGer A
  Conceptual Graph Editor, Accessed Online
  December 1999, URL http//www.cs.uah.edu/deluga
  ch/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.

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.ne
  t/sowa/cg/cgdpansw.htm
• Sowa 2000 Sowa, J., F. Knowledge
  Representation Logical, Philosophical, and
  Computational Foundations, Brooks/Cole, 2000.