COMPLETENESS AND DECIDABILITY OF TENSE LOGICS CLOSELY-RELATED TO LOGICS ABOVE K4

Tense logics formulated in the bimodal propositional language are inve stigated with respect to Kripke-completeness (completeness) and decida bility. It is proved that all minimal tense extensions of modal logics of finite width (in the sense of K. Kine) as well as all minimal tens e extensions of cofinal subframe logics (in the sense of M. Zakharyasc hev) are complete. The decidability of all finitely axiomatizable mini mal tense extensions of cofinal subframe logics is shown. A number of variations and extensions of these results are also presented.