[comp.lang.prolog] Information requested : theta subsumption

lucdr@kim.cs.kuleuven.ac.be (Luc De Raedt) (11/10/90)

Hello,

I'am looking for information concerning theta-subsumption of clauses
as defined by Plotkin in Machine Intelligence, 5 , 1970.

He states that a clause c subsumes a clause c' iff
there is a substitution t such that ct is a subset of c'.
c can also be considered as a generalization of c'.

My problem is that most  works on theta-subsumption
address either : 
	* subsumption tests
or	* finding the least genereralization of two clauses

I have a different problem:
I want to have a (computationally attractive) algorithm
to compute the following :

given : a clause c
find : all proper minimal generalizations of c 

Information concerning theoretical properties of theta subsumption of clauses
is also welcome.

Luc De Raedt
KULeuven
email :  lucdr@cs.kuleuven.ac.be