let X be non empty set ; :: thesis:
let S be SigmaField of X; :: thesis:
let M be sigma_Measure of S; :: thesis:
let k be positive Real; :: thesis:
set Z = AlmostZeroLpFunctions (M,k);
set V = RLSp_LpFunct (M,k);

let v, u be VECTOR of (RLSp_LpFunct (M,k)); :: thesis:
assume A1: ( v in AlmostZeroLpFunctions (M,k) & u in AlmostZeroLpFunctions (M,k) ) ; :: thesis:
then consider v1 being PartFunc of X,REAL such that
A2: ( v1 = v & v1 in Lp_Functions (M,k) & v1 a.e.= X --> 0,M ) ;
consider u1 being PartFunc of X,REAL such that
A3: ( u1 = u & u1 in Lp_Functions (M,k) & u1 a.e.= X --> 0,M ) by A1;
A4: v + u = v1 + u1 by Th29, A2, A3;
(X --> 0) + (X --> 0) = X --> 0 by LPSPACE1:33;
then ( v1 + u1 in Lp_Functions (M,k) & v1 + u1 a.e.= X --> 0,M ) by A4, A2, A3, LPSPACE1:31;
hence v + u in AlmostZeroLpFunctions (M,k) by A4; :: thesis:

end;

hence AlmostZeroLpFunctions (M,k) is add-closed by IDEAL_1:def 1; :: thesis:

let a be Real; :: thesis:
let u be VECTOR of (RLSp_LpFunct (M,k)); :: thesis:
assume u in AlmostZeroLpFunctions (M,k) ; :: thesis:
then consider u1 being PartFunc of X,REAL such that
A5: ( u1 = u & u1 in Lp_Functions (M,k) & u1 a.e.= X --> 0,M ) ;
A6: a * u = a (#) u1 by Th30, A5;
a (#) (X --> 0) = X --> 0 by LPSPACE1:33;
then ( a (#) u1 in Lp_Functions (M,k) & a (#) u1 a.e.= X --> 0,M ) by A6, A5, LPSPACE1:32;
hence a * u in AlmostZeroLpFunctions (M,k) by A6; :: thesis:

end;

hence AlmostZeroLpFunctions (M,k) is multi-closed ; :: thesis: