let Rseq be Function of [:NAT,NAT:],REAL; :: thesis: ( Rseq is non-decreasing & Rseq is P-convergent implies ( Rseq is bounded_below & Rseq is bounded_above ) )
assume a1: ( Rseq is non-decreasing & Rseq is P-convergent ) ; :: thesis: ( Rseq is bounded_below & Rseq is bounded_above )
then consider p being Real such that
a3: for e being Real st 0 < e holds
ex N being Nat st
for n, m being Nat st n >= N & m >= N holds
|.((Rseq . (n,m)) - p).| < e ;
consider N being Nat such that
a4: for n, m being Nat st n >= N & m >= N holds
|.((Rseq . (n,m)) - p).| < 1 by a3;
a5: for n, m being Nat st n >= N & m >= N holds
|.(Rseq . (n,m)).| < 1 + |.p.|
proof
let n, m be Nat; :: thesis: ( n >= N & m >= N implies |.(Rseq . (n,m)).| < 1 + |.p.| )
assume ( n >= N & m >= N ) ; :: thesis: |.(Rseq . (n,m)).| < 1 + |.p.|
then a6: |.((Rseq . (n,m)) - p).| < 1 by a4;
|.((Rseq . (n,m)) - p).| >= |.(Rseq . (n,m)).| - |.p.| by COMPLEX1:59;
then |.(Rseq . (n,m)).| - |.p.| < 1 by a6, XXREAL_0:2;
hence |.(Rseq . (n,m)).| < 1 + |.p.| by XREAL_1:19; :: thesis: verum
end;
deffunc H1( Element of NAT ) -> Element of NAT = c1;
deffunc H2( Nat) -> object = |.(Rseq . (1,c1)).|;
reconsider E2 = { H1(m) where m is Element of NAT : m <= N } as non empty finite Subset of NAT from ASYMPT_0:sch 2();
reconsider EE = [:E2,E2:] as finite set ;
c1: E2 is finite ;
deffunc H3( Element of NAT , Element of NAT ) -> object = |.(Rseq . (c1,c2)).|;
a9: { H3(m,n) where m, n is Element of NAT : ( m in E2 & n in E2 ) } is finite from FRAENKEL:sch 22(c1, c1);
set F = { H3(m,n) where m, n is Element of NAT : ( m in E2 & n in E2 ) } ;
N is Element of NAT by ORDINAL1:def 12;
then N in E2 ;
then b1: |.(Rseq . (N,N)).| in { H3(m,n) where m, n is Element of NAT : ( m in E2 & n in E2 ) } ;
now :: thesis: for x being object st x in { H3(m,n) where m, n is Element of NAT : ( m in E2 & n in E2 ) } holds
x is real
let x be object ; :: thesis: ( x in { H3(m,n) where m, n is Element of NAT : ( m in E2 & n in E2 ) } implies x is real )
assume x in { H3(m,n) where m, n is Element of NAT : ( m in E2 & n in E2 ) } ; :: thesis: x is real
then consider p, q being Element of NAT such that
a10: ( x = H3(p,q) & p in E2 & q in E2 ) ;
thus x is real by a10; :: thesis: verum
end;
then reconsider F = { H3(m,n) where m, n is Element of NAT : ( m in E2 & n in E2 ) } as non empty real-membered set by b1, MEMBERED:def 3;
reconsider M1 = sup F as Element of REAL by a9, XXREAL_2:16;
set M = max (M1,(1 + |.p.|));
a14: ( max (M1,(1 + |.p.|)) >= 1 + |.p.| & 1 + |.p.| >= 1 & max (M1,(1 + |.p.|)) >= M1 & max (M1,(1 + |.p.|)) >= M1 ) by XXREAL_0:25, XREAL_1:31, COMPLEX1:46;
c1: for n, m being Nat holds |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
proof
let n, m be Nat; :: thesis: |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
c0: ( n is Element of NAT & m is Element of NAT & N is Element of NAT ) by ORDINAL1:def 12;
per cases ( ( n >= N & m >= N ) or ( n < N & m < N ) or ( n < N & m >= N ) or ( n >= N & m < N ) ) ;
suppose ( n >= N & m >= N ) ; :: thesis: |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
then |.(Rseq . (n,m)).| < 1 + |.p.| by a5;
hence |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|)) by a14, XXREAL_0:2; :: thesis: verum
end;
suppose ( n < N & m < N ) ; :: thesis: |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
then ( n in E2 & m in E2 ) by c0;
then |.(Rseq . (n,m)).| in F ;
then a15: |.(Rseq . (n,m)).| <= M1 by XXREAL_2:4;
max (M1,(1 + |.p.|)) >= M1 by XXREAL_0:25;
hence |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|)) by a15, XXREAL_0:2; :: thesis: verum
end;
suppose a18: ( n < N & m >= N ) ; :: thesis: |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
then a19: ( Rseq . (n,N) <= Rseq . (n,m) & Rseq . (n,m) <= Rseq . (N,m) ) by a1;
( n in E2 & N in E2 ) by a18, c0;
then |.(Rseq . (n,N)).| in F ;
then a20: |.(Rseq . (n,N)).| <= M1 by XXREAL_2:4;
a21: |.(Rseq . (N,m)).| < 1 + |.p.| by a5, a18;
per cases ( |.(Rseq . (n,m)).| <= |.(Rseq . (n,N)).| or |.(Rseq . (n,m)).| <= |.(Rseq . (N,m)).| ) by a19, th28;
suppose |.(Rseq . (n,m)).| <= |.(Rseq . (n,N)).| ; :: thesis: |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
then |.(Rseq . (n,m)).| <= M1 by a20, XXREAL_0:2;
hence |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|)) by a14, XXREAL_0:2; :: thesis: verum
end;
suppose |.(Rseq . (n,m)).| <= |.(Rseq . (N,m)).| ; :: thesis: |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
then |.(Rseq . (n,m)).| <= 1 + |.p.| by a21, XXREAL_0:2;
hence |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|)) by a14, XXREAL_0:2; :: thesis: verum
end;
end;
end;
suppose a22: ( n >= N & m < N ) ; :: thesis: |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
then a23: ( Rseq . (N,m) <= Rseq . (n,m) & Rseq . (n,m) <= Rseq . (n,N) ) by a1;
( N in E2 & m in E2 ) by a22, c0;
then |.(Rseq . (N,m)).| in F ;
then a24: |.(Rseq . (N,m)).| <= M1 by XXREAL_2:4;
a25: |.(Rseq . (n,N)).| < 1 + |.p.| by a5, a22;
per cases ( |.(Rseq . (n,m)).| <= |.(Rseq . (N,m)).| or |.(Rseq . (n,m)).| <= |.(Rseq . (n,N)).| ) by a23, th28;
suppose |.(Rseq . (n,m)).| <= |.(Rseq . (N,m)).| ; :: thesis: |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
then |.(Rseq . (n,m)).| <= M1 by a24, XXREAL_0:2;
hence |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|)) by a14, XXREAL_0:2; :: thesis: verum
end;
suppose |.(Rseq . (n,m)).| <= |.(Rseq . (n,N)).| ; :: thesis: |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|))
then |.(Rseq . (n,m)).| <= 1 + |.p.| by a25, XXREAL_0:2;
hence |.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|)) by a14, XXREAL_0:2; :: thesis: verum
end;
end;
end;
end;
end;
now :: thesis: for a being ExtReal st a in Rseq .: [:NAT,NAT:] holds
( - (max (M1,(1 + |.p.|))) <= a & a <= max (M1,(1 + |.p.|)) )
let a be ExtReal; :: thesis: ( a in Rseq .: [:NAT,NAT:] implies ( - (max (M1,(1 + |.p.|))) <= a & a <= max (M1,(1 + |.p.|)) ) )
assume a in Rseq .: [:NAT,NAT:] ; :: thesis: ( - (max (M1,(1 + |.p.|))) <= a & a <= max (M1,(1 + |.p.|)) )
then consider x being Element of [:NAT,NAT:] such that
b2: ( x in [:NAT,NAT:] & a = Rseq . x ) by FUNCT_2:65;
consider n, m being object such that
b3: ( n in NAT & m in NAT & x = [n,m] ) by ZFMISC_1:def 2;
reconsider n = n, m = m as Element of NAT by b3;
|.(Rseq . (n,m)).| <= max (M1,(1 + |.p.|)) by c1;
hence ( - (max (M1,(1 + |.p.|))) <= a & a <= max (M1,(1 + |.p.|)) ) by b2, b3, ABSVALUE:5; :: thesis: verum
end;
then ( ( for a being ExtReal st a in Rseq .: [:NAT,NAT:] holds
- (max (M1,(1 + |.p.|))) <= a ) & ( for a being ExtReal st a in Rseq .: [:NAT,NAT:] holds
a <= max (M1,(1 + |.p.|)) ) ) ;
then ( - (max (M1,(1 + |.p.|))) is LowerBound of Rseq .: [:NAT,NAT:] & max (M1,(1 + |.p.|)) is UpperBound of Rseq .: [:NAT,NAT:] ) by XXREAL_2:def 1, XXREAL_2:def 2;
hence ( Rseq is bounded_below & Rseq is bounded_above ) by XXREAL_2:def 9, XXREAL_2:def 10; :: thesis: verum