Busy choice sequences refraining formulas and modalities

The purpose of this paper is to present some results instit theory, a theory of agency proposed by N. Belnap and M. Perloff. We will establish a correspondence between the numbers ofstit modalities and the complexity degrees ofbusy choice sequences in semantic structures, and consequently, a correspondence between the number of modes of actions/inactions instit theory and the complexity degrees ofbusy choice sequences in semantic structures.I would like to give thanks to professor N. Belnap for his special help and encouragement, and to the referees provided by this journal for their helpful suggestions in improving this paper.Presented byMelvin Fitting