Statements apply logic to connect Terms and Types. LSTS Statements provide rich algebraic manipulation of Terms and Types. Statements can be either logical theorems or axioms.

axiom @reflexive a:A. [True] = a == a;

forall @reflexive_int a:Integer. [True] = a == a @reflexive;


A Statement is formed by constructing

  • The keyword axiom or forall
  • An optional label
  • Optional parameters
  • The concluding Type
  • The Term definition


In Strict Mode statements must be constructed only from axioms, definitions, or from other theorems rooted in axioms. Deduction is label-directed, so it takes near-constant time. Every statement is validated separately, so unfounded theorems will generate separate errors. Theorems resulting from unfounded theorems can be made to generate a warning with the compiler flag: --warn-unfounded.