Knowledge compilation is a family of approaches for addressing the intractability of
a number of artificial intelligence

Artificial intelligence

Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

 problems.

A propositional model is compiled in an off-line phase in order to support some queries in polytime. Many ways of compiling a propositional models exist .
Among others: NNF, DNNF, d-DNNF, BDD

Binary decision diagram

In the field of computer science, a binary decision diagram or branching program, like a negation normal form or a propositional directed acyclic graph , is a data structure that is used to represent a Boolean function. On a more abstract level, BDDs can be considered as a compressed...

, MDD, DNF

Disjunctive normal form

In boolean logic, a disjunctive normal form is a standardization of a logical formula which is a disjunction of conjunctive clauses. As a normal form, it is useful in automated theorem proving. A logical formula is considered to be in DNF if and only if it is a disjunction of one or more...

 and CNF

Conjunctive normal form

In Boolean logic, a formula is in conjunctive normal form if it is a conjunction of clauses, where a clause is a disjunction of literals.As a normal form, it is useful in automated theorem proving...

.

Different compiled representations have different properties.
The three main properties are:

• The compactness of the representation
• The queries that are supported in polytime
• The transformations of the representations that can be performed in polytime