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Coincidenceandcommonfixedpoint...
Applying(6)and(01)wehave
(7)
00(H(Fx2njGp)jd(Tx2njSp)jD(Tx2njFx2n)j
D(SpjGp)jD(Tx2njGp)jD(SpjFx2n))
0(D(y2n+1jGp)jd(y2njz)jd(y2njy2n+1)j
D(SpjGp)jD(y2njGp)jd(Spjy2n+1)).
Lettingnweget
0(D(SpjGp)j0j0jD(SpjGp)jD(SpjGp)j0)0.
11
By(0a)weobtainSpGp.AsG(X)T(X),thereexistsqXsuch
thatz=Sp=Tq.
Using(6)and(01)wehave
(8)
00(H(FqjGx2n11)jd(TqjSx2n11)jD(TqjFq)j
D(Sx2n11jGx2n11)jD(TqjGx2n11)jD(Sx2n11jFq))
0(D(Fqjy2n)jd(Tqjy2n11)jD(TqjFq)j
d(y2n11jy2n)jd(Tqjy2n)jD(y2n11jFq)).
Lettingnweget
0(D(FqjTq)j0jD(FqjTq)j0j0jD(FqjTq))0.
By(0b)weobtainTqFq.SinceTandFareR-weaklycommutingof
type(AT)atqC(FjT),thereexistsanR>0suchthatD(TTqjFTq)
RD(TqjFq)andsoTzFz.Inthesamemanner,SzGz.IfSz=Tz,
thenSz=TzFznGzandifSz=Tz=z,thenzisacommonfixed
pointofSjTjFandG.
SupposethatT(X)iscomplete.Therefore,{y2n}convergestozT(X)
andsothereexistsqXsuchthatz=Tq.Applying(6)and(01)wehave
theinequality(8).Lettingnweget
0(D(FqjTq)j0jD(FqjTq)j0j0jD(FqjTq))0.
By(0b)weobtainTqFq.AsF(X)S(X),thereexistspXsuch
thatz=Sp=Tq.
Using(6)and(01)wegettheinequality(7).Lettingnweget
0(D(SpjGp)j0j0jD(SpjGp)jD(SpjGp)j0)0.
By(0a)weobtainSpGp.Therestoftheprooffollowsasinthecase
S(X)iscomplete.
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