Most present ILP systems are concerned with generating a single clause. Research is required into improved performance of multiple clause generation. Current ILP systems perform poorly in the presence of relevant long chains of literals, connected by shared variables. Recursive hypotheses are poorly handled by most ILP system. This is particularly important in the natural language domain.
Structural concepts result in complex clauses when encoded as literals.
These present problems to the search strategies used in current ILP systems. ILP systems have severe restrictions on the form of numeric constraints that can be used. ILP systems lack the ability te express probabilistic constraints. This effects the performance of ILP systems in the database discovery domain. ILP system require the ability to learn and make use of general constraints, rather than requiring large numbers of ground negative examples.