* Isar: method "assumption" (implicit closing of subproofs) takes non-atomic goal assumptions into account;
authorwenzelm
Wed, 13 Jun 2007 11:54:03 +0200
changeset 23369 227c51012cdb
parent 23368 ad690b9bca1c
child 23370 513a8ee192f1
* Isar: method "assumption" (implicit closing of subproofs) takes non-atomic goal assumptions into account; * Isar: implicit use of prems from the Isar proof context is considered a legacy feature;
NEWS
--- a/NEWS	Wed Jun 13 11:16:24 2007 +0200
+++ b/NEWS	Wed Jun 13 11:54:03 2007 +0200
@@ -154,6 +154,21 @@
 Command 'print_theory' outputs the normalized system of recursive
 equations, see section "definitions".
 
+* Isar: method "assumption" (and implicit closing of subproofs) now
+takes simple non-atomic goal assumptions into account: after applying
+an assumption as a rule the resulting subgoals are solved by atomic
+assumption steps.  This is particularly useful to finish 'obtain'
+goals, such as "!!x. (!!x. P x ==> thesis) ==> P x ==> thesis",
+without referring to the original premise "!!x. P x ==> thesis" in the
+Isar proof context.  POTENTIAL INCOMPATIBILITY: method "assumption" is
+more permissive.
+
+* Isar: implicit use of prems from the Isar proof context is
+considered a legacy feature.  Common applications like ``have A .''
+may be replaced by ``have A by fact'' or ``note `A`''.  In general,
+referencing facts explicitly here improves readability and
+maintainability of proof texts.
+
 * Isar: improper proof element 'guess' is like 'obtain', but derives
 the obtained context from the course of reasoning!  For example: