Logic programming that computational steps cannot be logically deduced. However, in concurrent logic programming, any result of a terminating computation is a logical consequence of the program, and any partial result of a partial computation is a logical consequence of the program and the residual goal (process network). Consequently, the indeterminacy of computations implies that not all logical consequences of the program can be deduced. Concurrent constraint logic programming combines concurrent logic programming and constraint logic programming, using constraints to control concurrency. A clause can contain a guard, which is a set of constraints that may block the applicability of the clause.
Logical biconditional Logical biconditional In logic and mathematics, the logical biconditional (sometimes known as the material biconditional) is the logical connective of two statements asserting "formula_1 if and only if formula_2", where formula_1 is an "antecedent" and formula_2 is a "consequent". This is often abbreviated "formula_1 iff formula_2". The operator is denoted using a doubleheaded arrow (↔), a prefixed E "E"pq"" (in Łukasiewicz notation or Bocheński notation), an equality sign (=), an equivalence sign (≡), or "EQV". It is logically equivalent to formula_7 and to formula_8 (or the XNOR (exclusive nor) boolean operator), meaning "both or neither". The only difference from material