let s be Real_Sequence; :: thesis: ( ( for n being Element of NAT holds
( s . n > 0 & s . n < 1 ) ) implies for n being Element of NAT holds
( (Partial_Product s) . n > 0 & (Partial_Product s) . n < 1 ) )
assume A1: for n being Element of NAT holds
( s . n > 0 & s . n < 1 ) ; :: thesis: for n being Element of NAT holds
( (Partial_Product s) . n > 0 & (Partial_Product s) . n < 1 )
defpred S₁[ Element of NAT ] means ( (Partial_Product s) . $1 > 0 & (Partial_Product s) . $1 < 1 );
(Partial_Product s) . 0 = s . 0 by Def1;
then A2: S₁[ 0 ] by A1;
A3: for n being Element of NAT st S₁[n] holds
S₁[n + 1]

proof

let n be Element of NAT ; :: thesis: ( S₁[n] implies S₁[n + 1] )
assume A4: ( (Partial_Product s) . n > 0 & (Partial_Product s) . n < 1 ) ; :: thesis: S₁[n + 1]
A5: (Partial_Product s) . (n + 1) = ((Partial_Product s) . n) * (s . (n + 1)) by Def1;
( s . (n + 1) > 0 & s . (n + 1) < 1 ) by A1;
hence S₁[n + 1] by A4, A5, XREAL_1:164; :: thesis: verum

end;

for n being Element of NAT holds S₁[n] from NAT_1:sch 1(A2, A3);
hence for n being Element of NAT holds
( (Partial_Product s) . n > 0 & (Partial_Product s) . n < 1 ) ; :: thesis: verum