Francis Jeffry Pelletier
There are various different formats for stating the method of semantic tableaux. The method Fitting uses is quite similar to the method I wish to employ, and there should be no difficulty in transforming the one into the other. In this note, I am interested in extending my method to a certain class of modal logics. In this extension we will only consider propositional logics - a fact that lends some considerable simplification to the description of the tableaux method.