Promise problems have been introduced in 1985 by S.Even e.a. as a generalization of decision problems. Using a very general approach we study solvability and unsolvability conditions for promise problems of set families and languages. We show, that cores of unsolvability are completely determined by partitions of cohesive sets. We prove the existence of cores in unsolvable promise problems assuming certain closure properties for the given set family. Connections to immune sets and complexity cores are presented. Furthermore, results about cohesiveness with respect to the language families from the Chomsky hierarchy are given.

Plate 1 SnAgCu-balls in the as delivered state with almost oxide-free but inhomogeneous surfaces Plate 2 SnAgCu-balls after 96 h/1508C ageing in air where the discoloration indicates excessive oxidation

No abstract

No abstract

No abstract