/usr/share/hol88-2.02.19940316/help/ENTRIES/EXT.doc is in hol88-help 2.02.19940316-35.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | \DOC EXT
\TYPE {EXT : (thm -> thm)}
\SYNOPSIS
Derives equality of functions from extentional equivalence.
\KEYWORDS
rule, extentionality.
\DESCRIBE
When applied to a theorem {A |- !x. t1 x = t2 x}, the inference rule
{EXT} returns the theorem {A |- t1 = t2}.
{
A |- !x. t1 x = t2 x
---------------------- EXT [where x is not free in t1 or t2]
A |- t1 = t2
}
\FAILURE
Fails if the theorem does not have the form indicated above, or
if the variable {x} is free either of the functions {t1} or {t2}.
\SEEALSO
AP_THM, ETA_CONV, FUN_EQ_CONV.
\ENDDOC
|