SET-ENFORCE-REDUNDANCY.html -- ACL2 Version 6.3

## SET-ENFORCE-REDUNDANCY

require most events to be redundant

    Major Section:  SWITCHES-PARAMETERS-AND-MODES

    General Forms:
    (set-enforce-redundancy nil)   ; do not require redundancy (default)
    (set-enforce-redundancy t)     ; most events (see below) must be redundant
    (set-enforce-redundancy :warn) ; warn for most non-redundant events

Note: This is an event! It does not print the usual event summary but nevertheless changes the ACL2 logical world and is so recorded.

    General Form:
    (set-enforce-redundancy flag)

where `flag` is `nil`, `t`, or `:warn`, as indicated above. This macro is essentially equivalent to

    (table acl2-defaults-table :enforce-redundancy flag)

and hence is `local` to any books and `encapsulate` events in which it occurs; see acl2-defaults-table. However, unlike the above simple call of the `table` event function (see table), no output results from a `set-enforce-redundancy` event.

`Set-enforce-redundancy` may be thought of as an event that merely sets a flag as indicated above, which determines whether most events, including `defun` and `defthm` events, are allowed to be redundant; see redundant-events. The exceptions are `deflabel`, `defpkg`, `encapsulate`, `include-book`, `push-untouchable`, `remove-untouchable`, `set-body`, and `table` events. Any other type of non-redundant event will cause an error if `flag` is `t` and a warning if `flag` is `nil`, except in the course of carrying out an `include-book` form.

Note that because `table` events that set the `acl2-defaults-table` are implicitly `local`, `set-enforce-redundancy` events are ignored when including books. However, the presence of the event `(set-enforce-redundancy t)` in a book guarantees that its subsequent definitions and theorems are redundant. This can be a useful property to maintain in library development, as we now describe.

An example of the use of this form can be found in the community books under directory `books/rtl/rel4/`. The intention in that directory has been to put all the gory details in subdirectories `support/` and `arithmetic/`, so that the books in subdirectory `lib/` contain only the ``exported'' definitions and theorems. This approach is useful for human readability. Moreover, suppose we want to prove new theorems in `lib/`. Typically we wish to prove the new theorems using the existing books in `lib/`; however, our methodology demands that the proofs go into books in `support/`. If every theorem in `lib/` is redundant, then we can develop the proofs in `lib/` but then when we are done, move each book with such proofs into `support/` as follows. In any such book, we first replace `include-book` forms referring to books in `lib/` by `include-book` forms referring to corresponding books in `support/` and/or `arithmetic/`. Then, we add suitable `in-theory` events to get us back into the original `lib/` proof environment.

The default behavior of the system is as though the `:enforce-redundancy` value is `nil`. The current behavior can be ascertained by evaluating the following form.

    (cdr (assoc-eq :enforce-redundancy (table-alist 'acl2-defaults-table wrld)))