kdrag.kernel.FreshVar

kdrag.kernel.FreshVar(prefix: str, sort: SortRef) → ExprRef

Generate a fresh variable. This is distinguished from FreshConst by the fact that it has freshness evidence. This is intended to be used for constants that represent arbitrary terms (implicitly universally quantified). For example, axioms like c_fresh = t should never be asserted about bare FreshVars as they imply a probably inconsistent axiom, whereas asserting such an axiom about FreshConst is ok, effectively defining a new rigid constant.

>>> FreshVar("x", smt.IntSort()).fresh_evidence
_FreshVarEvidence(v=x!...)

Parameters:

• prefix (str)

• sort (SortRef)

Return type:

ExprRef