fact: Definition mapsto (x y: adr) : pred world := fun w => x <> 0 /\ (forall a, a <> x -> lookup_fpm w a = None) /\ lookup_fpm w x = Some y.
imports: VST.msl.msl_direct FunctionalExtensionality CertiGraph.msl_ext.ramify_tactics CertiGraph.msl_ext.overlapping_direct CertiGraph.heap_model_direct.SeparationAlgebra Peano_dec