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.
Exportation (logic) Exportation (logic) Exportation is a valid rule of replacement in propositional logic. The rule allows conditional statements having conjunctive antecedents to be replaced by statements having conditional consequents and vice versa in logical proofs. It is the rule that: formula_1 Where "formula_2" is a metalogical symbol representing "can be replaced in a proof with." The "exportation" rule may be written in sequent notation: where formula_4 is a metalogical symbol meaning that formula_5 is a syntactic equivalent of formula_6 in some logical system; or in rule form: where the rule is that wherever an instance of "formula_9" appears on a line