reconsider R = {[0 ,1]} as non empty Relation ;
take
R
; :: thesis: R is complete
A1:
field R = {0 ,1}
by RELAT_1:32;
thus
R is confluent
:: according to REWRITE1:def 25 :: thesis: R is strongly-normalizing proof
let a,
b be
set ;
:: according to REWRITE1:def 22 :: thesis: ( a,b are_divergent_wrt R implies a,b are_convergent_wrt R )
given c being
set such that A2:
(
R reduces c,
a &
R reduces c,
b )
;
:: according to REWRITE1:def 8 :: thesis: a,b are_convergent_wrt R
per cases
( a = b or a <> b )
;
suppose
a <> b
;
:: thesis: a,b are_convergent_wrt Rthen
(
a <> c or
b <> c )
;
then
c in field R
by A2, Th19;
then
(
a in {0 ,1} &
b in {0 ,1} &
[0 ,1] in R )
by A1, A2, Th19, TARSKI:def 1;
then
( (
a = 0 or
a = 1 ) & (
b = 0 or
b = 1 ) &
R reduces 0 ,1 &
R reduces 1,1 )
by Th13, Th16, TARSKI:def 2;
hence
a,
b are_convergent_wrt R
by Def7;
:: thesis: verum end; end;
end;
A3:
R is irreflexive
R is co-well_founded
proof
let Y be
set ;
:: according to REWRITE1:def 16 :: thesis: ( Y c= field R & Y <> {} implies ex a being set st
( a in Y & ( for b being set st b in Y & a <> b holds
not [a,b] in R ) ) )
assume A4:
(
Y c= field R &
Y <> {} )
;
:: thesis: ex a being set st
( a in Y & ( for b being set st b in Y & a <> b holds
not [a,b] in R ) )
then reconsider Y' =
Y as non
empty set ;
consider y being
Element of
Y';
per cases
( 1 in Y or ( not 1 in Y & y in Y ) )
;
suppose A6:
( not 1
in Y &
y in Y )
;
:: thesis: ex a being set st
( a in Y & ( for b being set st b in Y & a <> b holds
not [a,b] in R ) )take
0
;
:: thesis: ( 0 in Y & ( for b being set st b in Y & 0 <> b holds
not [0 ,b] in R ) )thus
0 in Y
by A1, A4, A6, TARSKI:def 2;
:: thesis: for b being set st b in Y & 0 <> b holds
not [0 ,b] in Rlet b be
set ;
:: thesis: ( b in Y & 0 <> b implies not [0 ,b] in R )assume
b in Y
;
:: thesis: ( not 0 <> b or not [0 ,b] in R )hence
( not
0 <> b or not
[0 ,b] in R )
by A1, A4, A6, TARSKI:def 2;
:: thesis: verum end; end;
end;
then
R is irreflexive co-well_founded Relation
by A3;
hence
R is strongly-normalizing
; :: thesis: verum