reconsider s2 = NAT --> 1 as Real_Sequence by FUNCOP_1:57;
let s be Real_Sequence; :: thesis: for a being real number st a >= 1 & ( for n being Element of NAT st n >= 1 holds
s . n = n -Root a ) holds
( s is convergent & lim s = 1 )

let a be real number ; :: thesis: ( a >= 1 & ( for n being Element of NAT st n >= 1 holds
s . n = n -Root a ) implies ( s is convergent & lim s = 1 ) )

assume A1: a >= 1 ; :: thesis: ( ex n being Element of NAT st
( n >= 1 & not s . n = n -Root a ) or ( s is convergent & lim s = 1 ) )

deffunc H1( Element of NAT ) -> Element of REAL = (a - 1) / ($1 + 1);
consider s1 being Real_Sequence such that
A2: for n being Element of NAT holds s1 . n = H1(n) from SEQ_1:sch 1();
set s3 = s2 + s1;
A3: s1 is convergent by A2, SEQ_4:46;
then A4: s2 + s1 is convergent by SEQ_2:19;
assume A5: for n being Element of NAT st n >= 1 holds
s . n = n -Root a ; :: thesis: ( s is convergent & lim s = 1 )
A6: now
let n be Element of NAT ; :: thesis: ( s2 . n <= (s ^\ 1) . n & (s ^\ 1) . n <= (s2 + s1) . n )
A7: n + 1 >= 0 + 1 by XREAL_1:8;
set b = ((s ^\ 1) . n) - 1;
A8: (s ^\ 1) . n = s . (n + 1) by NAT_1:def 3
.= (n + 1) -Root a by A5, A7 ;
then A9: (s ^\ 1) . n >= 1 by A1, A7, Th38;
then ((s ^\ 1) . n) - 1 >= 0 by XREAL_1:50;
then A10: - 1 < ((s ^\ 1) . n) - 1 by XXREAL_0:2;
a = (1 + (((s ^\ 1) . n) - 1)) |^ (n + 1) by A1, A7, A8, Lm2;
then a >= 1 + ((n + 1) * (((s ^\ 1) . n) - 1)) by A10, Th24;
then a - 1 >= (1 + ((n + 1) * (((s ^\ 1) . n) - 1))) - 1 by XREAL_1:11;
then (a - 1) * ((n + 1) " ) >= ((n + 1) " ) * ((n + 1) * (((s ^\ 1) . n) - 1)) by XREAL_1:66;
then (a - 1) * ((n + 1) " ) >= (((n + 1) " ) * (n + 1)) * (((s ^\ 1) . n) - 1) ;
then (a - 1) * ((n + 1) " ) >= 1 * (((s ^\ 1) . n) - 1) by XCMPLX_0:def 7;
then ((a - 1) / (n + 1)) + 1 >= (((s ^\ 1) . n) - 1) + 1 by XREAL_1:8;
then (s2 . n) + ((a - 1) / (n + 1)) >= (s ^\ 1) . n by FUNCOP_1:13;
then (s2 . n) + (s1 . n) >= (s ^\ 1) . n by A2;
hence ( s2 . n <= (s ^\ 1) . n & (s ^\ 1) . n <= (s2 + s1) . n ) by A9, FUNCOP_1:13, SEQ_1:11; :: thesis: verum
end;
lim s1 = 0 by A2, SEQ_4:46;
then A11: lim (s2 + s1) = (s2 . 0 ) + 0 by A3, SEQ_4:59
.= 1 by FUNCOP_1:13 ;
A12: lim s2 = s2 . 0 by SEQ_4:41
.= 1 by FUNCOP_1:13 ;
then A13: s ^\ 1 is convergent by A4, A11, A6, SEQ_2:33;
hence s is convergent by SEQ_4:35; :: thesis: lim s = 1
lim (s ^\ 1) = 1 by A4, A11, A12, A6, SEQ_2:34;
hence lim s = 1 by A13, SEQ_4:36; :: thesis: verum