From: Claudio Sacerdoti Coen <claudio.sacerdoticoen@unibo.it>
Date: Tue, 13 Mar 2007 16:17:42 +0000 (+0000)
Subject: Role of
X-Git-Tag: make_still_working~6424
X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=bccb5e2838b8552896ee797af5114e7c7ca037b6;p=helm.git

Role of
 - replace
 - replace_lifting
 - replace_lifting_csc
clarified with comments. None of this function is the inverse of subst :-)
---

diff --git a/helm/software/components/tactics/proofEngineReduction.ml b/helm/software/components/tactics/proofEngineReduction.ml
index c359313dd..dbc98f722 100644
--- a/helm/software/components/tactics/proofEngineReduction.ml
+++ b/helm/software/components/tactics/proofEngineReduction.ml
@@ -122,7 +122,11 @@ let alpha_equivalence =
 
 exception WhatAndWithWhatDoNotHaveTheSameLength;;
 
-(* "textual" replacement of several subterms with other ones *)
+(* Replaces "textually" in "where" every term in "what" with the corresponding
+   term in "with_what". The terms in "what" ARE NOT lifted when binders are
+   crossed. The terms in "with_what" ARE NOT lifted when binders are crossed.
+   Every free variable in "where" IS NOT lifted by nnn.
+*)
 let replace ~equality ~what ~with_what ~where =
   let find_image t =
    let rec find_image_aux =
@@ -182,8 +186,13 @@ let replace ~equality ~what ~with_what ~where =
     aux where
 ;;
 
-(* replaces in a term a term with another one. *)
-(* Lifting are performed as usual.             *)
+(* Replaces in "where" every term in "what" with the corresponding
+   term in "with_what". The terms in "what" ARE lifted when binders are
+   crossed. The terms in "with_what" ARE lifted when binders are crossed.
+   Every free variable in "where" IS NOT lifted by nnn.
+   Thus "replace_lifting_csc 1 ~with_what:[Rel 1; ... ; Rel 1]" is the
+   inverse of subst up to the fact that free variables in "where" are NOT
+   lifted.  *)
 let replace_lifting ~equality ~what ~with_what ~where =
   let find_image what t =
    let rec find_image_aux =
@@ -278,8 +287,12 @@ let replace_lifting ~equality ~what ~with_what ~where =
   substaux 1 what where
 ;;
 
-(* replaces in a term a list of terms with other ones. *)
-(* Lifting are performed as usual.                     *)
+(* Replaces in "where" every term in "what" with the corresponding
+   term in "with_what". The terms in "what" ARE NOT lifted when binders are
+   crossed. The terms in "with_what" ARE lifted when binders are crossed.
+   Every free variable in "where" IS lifted by nnn.
+   Thus "replace_lifting_csc 1 ~with_what:[Rel 1; ... ; Rel 1]" is the
+   inverse of subst up to the fact that "what" terms are NOT lifted. *)
 let replace_lifting_csc nnn ~equality ~what ~with_what ~where =
   let find_image t =
    let rec find_image_aux =
diff --git a/helm/software/components/tactics/proofEngineReduction.mli b/helm/software/components/tactics/proofEngineReduction.mli
index c0318bdfe..39beb84aa 100644
--- a/helm/software/components/tactics/proofEngineReduction.mli
+++ b/helm/software/components/tactics/proofEngineReduction.mli
@@ -35,15 +35,36 @@ exception AlreadySimplified
 exception WhatAndWithWhatDoNotHaveTheSameLength;;
 
 val alpha_equivalence: Cic.term -> Cic.term -> bool
+
+(* Replaces "textually" in "where" every term in "what" with the corresponding
+   term in "with_what". The terms in "what" ARE NOT lifted when binders are
+   crossed. The terms in "with_what" ARE NOT lifted when binders are crossed.
+   Every free variable in "where" IS NOT lifted by nnn. *)
 val replace :
   equality:('a -> Cic.term -> bool) ->
   what:'a list -> with_what:Cic.term list -> where:Cic.term -> Cic.term
+
+(* Replaces in "where" every term in "what" with the corresponding
+   term in "with_what". The terms in "what" ARE lifted when binders are
+   crossed. The terms in "with_what" ARE lifted when binders are crossed.
+   Every free variable in "where" IS NOT lifted by nnn.
+   Thus "replace_lifting_csc 1 ~with_what:[Rel 1; ... ; Rel 1]" is the
+   inverse of subst up to the fact that free variables in "where" are NOT
+   lifted. *)
 val replace_lifting :
   equality:(Cic.term -> Cic.term -> bool) ->
   what:Cic.term list -> with_what:Cic.term list -> where:Cic.term -> Cic.term
+
+(* Replaces in "where" every term in "what" with the corresponding
+   term in "with_what". The terms in "what" ARE NOT lifted when binders are
+   crossed. The terms in "with_what" ARE lifted when binders are crossed.
+   Every free variable in "where" IS lifted by nnn.
+   Thus "replace_lifting_csc 1 ~with_what:[Rel 1; ... ; Rel 1]" is the
+   inverse of subst up to the fact that "what" terms are NOT lifted. *)
 val replace_lifting_csc :
   int -> equality:(Cic.term -> Cic.term -> bool) ->
   what:Cic.term list -> with_what:Cic.term list -> where:Cic.term -> Cic.term
+
 val subst_inv :
   equality:(Cic.term -> Cic.term -> bool) ->
   what:Cic.term list -> int -> Cic.term -> Cic.term