491 Knowledge Representation (Autumn 2017)

These notes and exercises are copyright Marek Sergot.  You may use them as long as they are
not sold for profit and the title slide with the names and affiliations appears on them as in the file.

Please let me know of any typographical or other errors in these notes. mjs "at" doc.ic.ac.uk

• Introduction/Overview:   Slides (don't print!)    (printable)
  These slides are just for introduction, background, and motivation. There is nothing here
  that needs to be learned. Everything important will be covered more carefully and in detail
  during the lectures.

Lecture notes

• Preliminaries : Models, theories, consequence relations v1.0h
• Logic Databases (Knowledge Bases) v1.0e
• Negation as failure (Normal logic programs) v1.3f
• Minimal models and fixpoint semantics for definite logic programs v1.0h
  
• Stratified logic programs v1.0c
  
• Stable models ('Answer sets') v1.2c
  Splitting Sets v1.0i
  
• Extended Logic Programs v1.6b
• ASP (Answer Set Programming) Solvers v1.0b
  Version v1.0b: I added a few brief comments on choice rules and cardinality constraints.
  (Last two pages. The rest is unchanged.)
• Extended logic programs: Disjunction
  I have added a few brief notes on the treatment of disjunction in logic programs.
  These are all points which have come up during the lectures.
  11 Dec 2017: There was a typo in the notes, now fixed.
  The second example of 'shifting' has only one answer set, {a}.
  Thanks to David Williamson for spotting this typo.
• Default Logic (Reiter) v1.1j
  Version v1.1j: I added two short final remarks at pp21 and 22, just before Appendix.
  This is a summary of examples I discussed on the whiteboard.
• Non-monotonic Consequence Relations v1.1d
• The Action Language C+ (Outline)
  This first set of slides was for orientation only. It is just a sketch.
  Everything is explained more carefully and in more detail in the lecture notes that follow.
• The Action Language C+ v2.1
• Addendum: Translation to logic program (ASP) v1.1
  Version v1.1b: This is a newer version than was originally posted. The original version
  relied on some previous material not covered any more.
  The newer version has cleaned up the account of dealing with multivalued signatures.
  However those details are for background only.
  For examination purposes, concentrate only on the translation of Boolean signatures.
  Details of the treatment of multi-valued constants will not tested in the exam.
  (There would be too much to write in examination conditions.)

Tutorial exercises

• Logic databases (Revision)    (Solutions)
• Consequence relations    (Solutions)
• Logic databases    (Solutions)
  
• Defaults and exceptions with negation as failure
  (Solutions are discussed in the lecture notes)
• Fixpoint semantics for definite programs    (Solutions)
  
• Stratified databases    (Solutions)
  
• Stable models (No solution sheet; examples are discussed under `splitting sets')
• Splitting Sets (Solutions included)
• Extended Logic Programs (Solutions, with comments, included)
• Default Logic    (Solutions included)
• Non-monotonic Consequence Relations    (Solutions included)
• The Action Language C+    (Solutions, with commentary, included)

Answer Set Solver: clingo

It is installed on /vol/lab/CLASP. See README file in that directory.

Assessed coursework (2017-18)

• Assessed coursework

  This exercise is intended to provide a directed exploration of issues in the
  formalisation of default persistence (`inertia') and temporal reasoning,
  and thereby to complement the material presented in lectures.