query or set tau system status

(tau-status :system t)
(tau-status :auto-mode nil)
(tau-status :system t :auto-mode nil)

General Form:
(tau-status :system a :auto-mode b)
where a and b are Booleans. Both keyword arguments are optional and they may be presented in either order. Value a controls whether the tau-system is used during subsequent proofs. Value b controls whether the tau rules are automatically created as rules of other rule-classes are added.

There are two important flags associated with the tau-system: (a) whether the tau system is used in proof attempts, and (b) whether the tau system is automatically extending its data base when other classes of rules are added. These two flags are independent. For example, the tau system may be disabled in proof attempts even though it is actively (and silently) extending its data base in as rules of other classes are added.

This macro allows you to inspect or set the two flags. Flag (a) is actually toggled by enabling or disabling the executable-counterpart of tau-system. Flag (b) is toggled with the function set-tau-auto-mode, which manipulates the acl2-defaults-table.

This macro expands into zero, one, or two events, as required by the supplied values of flags a and b.

If no arguments are supplied the form is not an event and simply returns (as an ``error triple'' (mv nil ans state)) the current settings of the two flags. For example:

ACL2 !>(tau-system)

intended to be self-explanatory.