## 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))`

.