let n be Nat; for a being Real
for x, y being Element of (REAL-NS n)
for x0, y0 being Element of (RealVectSpace (Seg n)) st x = x0 & y = y0 holds
( the carrier of (REAL-NS n) = the carrier of (RealVectSpace (Seg n)) & 0. (REAL-NS n) = 0. (RealVectSpace (Seg n)) & x + y = x0 + y0 & a * x = a * x0 & - x = - x0 & x - y = x0 - y0 )
let a be Real; for x, y being Element of (REAL-NS n)
for x0, y0 being Element of (RealVectSpace (Seg n)) st x = x0 & y = y0 holds
( the carrier of (REAL-NS n) = the carrier of (RealVectSpace (Seg n)) & 0. (REAL-NS n) = 0. (RealVectSpace (Seg n)) & x + y = x0 + y0 & a * x = a * x0 & - x = - x0 & x - y = x0 - y0 )
let x, y be Element of (REAL-NS n); for x0, y0 being Element of (RealVectSpace (Seg n)) st x = x0 & y = y0 holds
( the carrier of (REAL-NS n) = the carrier of (RealVectSpace (Seg n)) & 0. (REAL-NS n) = 0. (RealVectSpace (Seg n)) & x + y = x0 + y0 & a * x = a * x0 & - x = - x0 & x - y = x0 - y0 )
let x0, y0 be Element of (RealVectSpace (Seg n)); ( x = x0 & y = y0 implies ( the carrier of (REAL-NS n) = the carrier of (RealVectSpace (Seg n)) & 0. (REAL-NS n) = 0. (RealVectSpace (Seg n)) & x + y = x0 + y0 & a * x = a * x0 & - x = - x0 & x - y = x0 - y0 ) )
assume A1:
( x = x0 & y = y0 )
; ( the carrier of (REAL-NS n) = the carrier of (RealVectSpace (Seg n)) & 0. (REAL-NS n) = 0. (RealVectSpace (Seg n)) & x + y = x0 + y0 & a * x = a * x0 & - x = - x0 & x - y = x0 - y0 )
A2:
RLSStruct(# the carrier of (REAL-NS n), the ZeroF of (REAL-NS n), the U5 of (REAL-NS n), the Mult of (REAL-NS n) #) = RealVectSpace (Seg n)
by Th15;
set V = REAL-NS n;
set W = RealVectSpace (Seg n);
thus
( the carrier of (REAL-NS n) = the carrier of (RealVectSpace (Seg n)) & 0. (REAL-NS n) = 0. (RealVectSpace (Seg n)) )
by A2; ( x + y = x0 + y0 & a * x = a * x0 & - x = - x0 & x - y = x0 - y0 )
thus
x + y = x0 + y0
by A1, A2; ( a * x = a * x0 & - x = - x0 & x - y = x0 - y0 )
thus
a * x = a * x0
by A1, A2; ( - x = - x0 & x - y = x0 - y0 )
thus - x =
(- 1) * x
by RLVECT_1:16
.=
(- 1) * x0
by A1, A2
.=
- x0
by RLVECT_1:16
; x - y = x0 - y0
- y =
(- 1) * y
by RLVECT_1:16
.=
(- 1) * y0
by A1, A2
.=
- y0
by RLVECT_1:16
;
hence
x - y = x0 - y0
by A1, A2; verum