TAU-DATA.html -- ACL2 Version 6.3

## TAU-DATA

to see what tau knows about a function symbol

    Major Section:  HISTORY

    Examples:
    (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))`.