G. E. Hughes, M. J. Cresswell, "A Companion to Modal Logic"
English | 1985 | ISBN: 0416375006, 0416375103 | 220 pages | scan PDF | 5,6 MB
An earlier book of ours, entitled An IntroductIOn to Modol Logic (IM L), was published in 1968. When we wrote It, we were able to give a reasonably comprehensive survey of the state of modal logic at that time. We very much doubt, however, whether any comparable survey would be possible today, for, since 1968, the subject has developed vigorously in a wide variety of directions.