... For the sign (8) to play a communicative role, one ad- ditional kind of information is needed. Typically, heads give information about relation.~, while complements give information about the ... systems, which we regard for theoretical purposes as thinking organisms, (Frege referred to his own logical formalism, Begriffsschrift, an a "formula language for pure thought" [Frege ... expressions with more complex NFLT translations. For rules to work, each sign must contain information about how it figures in the rules. We call this information the (syntactic) category of the...