to see what tau knows about a function symbol
Major Section:  HISTORY

(tau-data binary-+)

General Form:
(tau-data fn)

This macro returns a list structure that indicates what facts about the symbol fn are known to the tau system. Fn should either be a function symbol or else a macro associated with fn; see macro-aliases-table. See introduction-to-the-tau-system for background details.

The list structure should be self-explanatory given the following brief comments. The ``index'' of a function, when non-nil, means the function is a monadic Boolean function treated by the tau system as a tau predicate.

The ``positive'' and ``negative implicants'' are conjunctions that indicate the tau implied by the given one or its negation.

The ``signatures'' entry is a formula indicating all the known signatures. If the signatures formula is T it means there are no known signatures. (Signatures is the conjunction of all signature rules and the empty conjunction is T.) If you wish to see a long list of all the runes from which some tau information has been gleaned, evaluate (global-val 'tau-runes (w state)).