let C be Simple_closed_curve; for i being Element of NAT
for r, t being real number st r > 0 & t > 0 holds
ex n being Element of NAT st
( i < n & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 1,2) < r & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 2,1) < t )
let i be Element of NAT ; for r, t being real number st r > 0 & t > 0 holds
ex n being Element of NAT st
( i < n & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 1,2) < r & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 2,1) < t )
let r, t be real number ; ( r > 0 & t > 0 implies ex n being Element of NAT st
( i < n & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 1,2) < r & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 2,1) < t ) )
assume that
A1:
r > 0
and
A2:
t > 0
; ex n being Element of NAT st
( i < n & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 1,2) < r & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 2,1) < t )
consider n being Element of NAT such that
1 < n
and
A3:
dist ((Gauge C,n) * 1,1),((Gauge C,n) * 1,2) < r
and
A4:
dist ((Gauge C,n) * 1,1),((Gauge C,n) * 2,1) < t
by A1, A2, GOBRD14:21;
per cases
( i < n or i >= n )
;
suppose A5:
i < n
;
ex n being Element of NAT st
( i < n & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 1,2) < r & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 2,1) < t )take
n
;
( i < n & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 1,2) < r & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 2,1) < t )thus
(
i < n &
dist ((Gauge C,n) * 1,1),
((Gauge C,n) * 1,2) < r &
dist ((Gauge C,n) * 1,1),
((Gauge C,n) * 2,1) < t )
by A3, A4, A5;
verum end; suppose A6:
i >= n
;
ex n being Element of NAT st
( i < n & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 1,2) < r & dist ((Gauge C,n) * 1,1),((Gauge C,n) * 2,1) < t )take
i + 1
;
( i < i + 1 & dist ((Gauge C,(i + 1)) * 1,1),((Gauge C,(i + 1)) * 1,2) < r & dist ((Gauge C,(i + 1)) * 1,1),((Gauge C,(i + 1)) * 2,1) < t )A7:
(
i > n or
i = n )
by A6, XXREAL_0:1;
then A8:
dist ((Gauge C,i) * 1,1),
((Gauge C,i) * 2,1) <= dist ((Gauge C,n) * 1,1),
((Gauge C,n) * 2,1)
by Th11;
A9:
dist ((Gauge C,i) * 1,1),
((Gauge C,i) * 1,2) <= dist ((Gauge C,n) * 1,1),
((Gauge C,n) * 1,2)
by A7, Th9;
thus A10:
i < i + 1
by NAT_1:13;
( dist ((Gauge C,(i + 1)) * 1,1),((Gauge C,(i + 1)) * 1,2) < r & dist ((Gauge C,(i + 1)) * 1,1),((Gauge C,(i + 1)) * 2,1) < t )then
dist ((Gauge C,(i + 1)) * 1,1),
((Gauge C,(i + 1)) * 1,2) < dist ((Gauge C,i) * 1,1),
((Gauge C,i) * 1,2)
by Th9;
then A11:
dist ((Gauge C,(i + 1)) * 1,1),
((Gauge C,(i + 1)) * 1,2) < dist ((Gauge C,n) * 1,1),
((Gauge C,n) * 1,2)
by A9, XXREAL_0:2;
dist ((Gauge C,(i + 1)) * 1,1),
((Gauge C,(i + 1)) * 2,1) < dist ((Gauge C,i) * 1,1),
((Gauge C,i) * 2,1)
by A10, Th11;
then
dist ((Gauge C,(i + 1)) * 1,1),
((Gauge C,(i + 1)) * 2,1) < dist ((Gauge C,n) * 1,1),
((Gauge C,n) * 2,1)
by A8, XXREAL_0:2;
hence
(
dist ((Gauge C,(i + 1)) * 1,1),
((Gauge C,(i + 1)) * 1,2) < r &
dist ((Gauge C,(i + 1)) * 1,1),
((Gauge C,(i + 1)) * 2,1) < t )
by A3, A4, A11, XXREAL_0:2;
verum end; end;