Cohesiveness in promise problems

Ulrike Brandt, Hermann K.-G. Walter
2013 RAIRO - Theoretical Informatics and Applications  
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
more » ... es are presented. Furthermore, results about cohesiveness with respect to the language families from the Chomsky hierarchy are given.
doi:10.1051/ita/2013042 fatcat:ymmvzt76brdzpgr7w3lkwmf6ze