let n, j be Element of NAT ; for f being Element of REAL * st OuterVx f,n <> {} & j = Argmin (OuterVx f,n),f,n holds
( j in dom f & 1 <= j & j <= n & f . j <> - 1 & f . (n + j) <> - 1 )
let f be Element of REAL * ; ( OuterVx f,n <> {} & j = Argmin (OuterVx f,n),f,n implies ( j in dom f & 1 <= j & j <= n & f . j <> - 1 & f . (n + j) <> - 1 ) )
set IN = OuterVx f,n;
assume
( OuterVx f,n <> {} & j = Argmin (OuterVx f,n),f,n )
; ( j in dom f & 1 <= j & j <= n & f . j <> - 1 & f . (n + j) <> - 1 )
then
ex i being Element of NAT st
( i = j & i in OuterVx f,n & ( for k being Element of NAT st k in OuterVx f,n holds
f /. ((2 * n) + i) <= f /. ((2 * n) + k) ) & ( for k being Element of NAT st k in OuterVx f,n & f /. ((2 * n) + i) = f /. ((2 * n) + k) holds
i <= k ) )
by Def10;
then
ex k being Element of NAT st
( j = k & k in dom f & 1 <= k & k <= n & f . k <> - 1 & f . (n + k) <> - 1 )
;
hence
( j in dom f & 1 <= j & j <= n & f . j <> - 1 & f . (n + j) <> - 1 )
; verum