changeset 19:55a0d814fce7 default tip

...
author Shinji KONO <kono@ie.u-ryukyu.ac.jp>
date Wed, 16 Dec 2020 16:16:43 +0900
parents 6cd5b63ecc38
children
files Logic.agda simple-logic.agda
diffstat 2 files changed, 2 insertions(+), 2 deletions(-) [+]
line wrap: on
line diff
--- a/Logic.agda	Sat Aug 22 13:34:12 2020 +0900
+++ b/Logic.agda	Wed Dec 16 16:16:43 2020 +0900
@@ -36,7 +36,7 @@
    (e ∧ e₁) [ xv / v ]     = (  e [ xv / v ]) ∧ (  e₁ [ xv / v ])
    (e ∨ e₁) [ xv / v ]     = (  e [ xv / v ]) ∨ (  e₁ [ xv / v ])
    (¬ e) [ xv / v ]        = ¬ (  e [ xv / v ])
-   (All x => e) [ xv / v ]   = All x =>   (  e [ xv / v ])
+   (All x => e) [ xv / v ]   = All x =>   (  e [ xv / v ])   -- we should protect variable x from replacement
    (Exist x => e) [ xv / v ] = Exist x => (  e [ xv / v ])
 
    m :  Statement  → Bool
--- a/simple-logic.agda	Sat Aug 22 13:34:12 2020 +0900
+++ b/simple-logic.agda	Wed Dec 16 16:16:43 2020 +0900
@@ -44,7 +44,7 @@
 (x ∧ y) [ n / v ] = (x [ n / v ] ) ∧  (x [ n / v ])
 (x ∨ y) [ n / v ] = (x [ n / v ] ) ∨  (x [ n / v ])
 (¬ x) [ n / v ] = ¬ (x [ n / v ] )
-(all x => y) [ n / v ] = all x => (y [ n / v ])
+(all x => y) [ n / v ] = all x => (y [ n / v ])    -- we should protect variable x from replacement
 (∃ x => y) [ n / v ] =  ∃ x =>    (y [ n / v ])
 
 {-# TERMINATING #-}