let f be real-valued FinSequence; for r1, r2 being Real st f = <*r1,r2*> holds
( min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) )
let r1, r2 be Real; ( f = <*r1,r2*> implies ( min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) ) )
assume A1:
f = <*r1,r2*>
; ( min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) )
then A2:
len f = 2
by FINSEQ_1:44;
then A3:
f . 1 >= f . (min_p f)
by Th2;
A4:
f . 2 = r2
by A1;
A5:
min_p f in dom f
by A2, Def2;
then A6:
1 <= min_p f
by FINSEQ_3:25;
A7:
f . 2 >= f . (min_p f)
by A2, Th2;
A8:
f . 1 = r1
by A1;
A9:
min_p f <= len f
by A5, FINSEQ_3:25;
per cases
( r1 <= r2 or r1 > r2 )
;
suppose
r1 <= r2
;
( min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) )then A10:
min (
r1,
r2)
>= min f
by A8, A3, XXREAL_0:def 9;
now ( ( min_p f < len f & min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) ) or ( min_p f >= len f & min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) ) )per cases
( min_p f < len f or min_p f >= len f )
;
case
min_p f < len f
;
( min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) )then
min_p f < 1
+ 1
by A1, FINSEQ_1:44;
then
min_p f <= 1
by NAT_1:13;
then A11:
min_p f = 1
by A6, XXREAL_0:1;
then
min f >= min (
r1,
r2)
by A8, XXREAL_0:17;
then
min f = min (
r1,
r2)
by A10, XXREAL_0:1;
hence
(
min f = min (
r1,
r2) &
min_p f = IFEQ (
r1,
(min (r1,r2)),1,2) )
by A8, A11, FUNCOP_1:def 8;
verum end; case
min_p f >= len f
;
( min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) )then A12:
min_p f = 2
by A2, A9, XXREAL_0:1;
then
min f >= min (
r1,
r2)
by A4, XXREAL_0:17;
then A13:
min f = min (
r1,
r2)
by A10, XXREAL_0:1;
1
in dom f
by A2, FINSEQ_3:25;
then
r1 <> r2
by A2, A8, A4, A12, Def2;
hence
(
min f = min (
r1,
r2) &
min_p f = IFEQ (
r1,
(min (r1,r2)),1,2) )
by A4, A12, A13, FUNCOP_1:def 8;
verum end; end; end; hence
(
min f = min (
r1,
r2) &
min_p f = IFEQ (
r1,
(min (r1,r2)),1,2) )
;
verum end; suppose
r1 > r2
;
( min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) )then A14:
min (
r1,
r2)
>= min f
by A4, A7, XXREAL_0:def 9;
now ( ( min_p f < len f & min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) ) or ( min_p f >= len f & min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) ) )per cases
( min_p f < len f or min_p f >= len f )
;
case
min_p f < len f
;
( min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) )then
min_p f < 1
+ 1
by A1, FINSEQ_1:44;
then
min_p f <= 1
by NAT_1:13;
then A15:
min_p f = 1
by A6, XXREAL_0:1;
then
min f >= min (
r1,
r2)
by A8, XXREAL_0:17;
then
min f = min (
r1,
r2)
by A14, XXREAL_0:1;
hence
(
min f = min (
r1,
r2) &
min_p f = IFEQ (
r1,
(min (r1,r2)),1,2) )
by A8, A15, FUNCOP_1:def 8;
verum end; case
min_p f >= len f
;
( min f = min (r1,r2) & min_p f = IFEQ (r1,(min (r1,r2)),1,2) )then A16:
min_p f = 2
by A2, A9, XXREAL_0:1;
then
min f >= min (
r1,
r2)
by A4, XXREAL_0:17;
then A17:
min f = min (
r1,
r2)
by A14, XXREAL_0:1;
1
in dom f
by A2, FINSEQ_3:25;
then
r1 <> r2
by A2, A8, A4, A16, Def2;
hence
(
min f = min (
r1,
r2) &
min_p f = IFEQ (
r1,
(min (r1,r2)),1,2) )
by A4, A16, A17, FUNCOP_1:def 8;
verum end; end; end; hence
(
min f = min (
r1,
r2) &
min_p f = IFEQ (
r1,
(min (r1,r2)),1,2) )
;
verum end; end;