A Basic Constraint Language

• We will use a basic language whose components are:
  • Variables, starting with uppercase: $X, Y, Speed$
  • Constants, either numbers or names starting with lowercase: $1, 199, cat, a\_dog$
    Those constants are the Domain of the language
  • Atoms, which have the form $p(X_1, \ldots, X_n)$, where:
    • $p$ is the name of the atom, and $n$ its arity (i.e. it admits $n$ arguments) -- usually written $p/n$
    • $X_1, \ldots, X_n$ are either constants or variables
    • Example:

      $hates(dog, cat)$

      $predates(big\_fish, small\_fish)$

  • Constraints: we will use only $=/2$ (syntactic equality)
• We will augment this language later