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FASCICULI
MATHEMATICI
Nr41
2009
AbdelkrimAlioucheandValeriuPopa
COINCIDENCEANDCOMMONFIXEDPOINT
THEOREMSVIAR-WEAKCOMMUTATIVITY
OFTYPE(AT)
Abstract.Weprovecommonfixedpointtheoremsfortwopairs
ofhybridmappingssatisfyingimplicitrelationsincompletemetric
spacesusingtheconceptofRweakcommutativityoftypeAT
andwecorrecterrorsof[1],[3]and[8].Ourtheoremsgeneralize
resultsof[1-3],[8],[12-16]and[21].
Keywords:hybridmappings,commonfixedpoint,Rweakly
commutingoftypeAT,metricspace.
AMSMathematicsSubjectClassification:54H25,47H10.
1.Introductionandpreliminaries
Let(Xjd)beametricspace.ForxXandAX,D(xjA)=inf{d(xjy)j
yA}.
LetCB(X)bethesetofallnonemptyclosedandboundedsubsetsofX.
LetHbetheHausdorffmetricwithrespecttoddefinedby
H(AjB)=max{sup
aA
D(ajB)jsup
bB
D(Ajb)}forallAjBCB(X).
Itiswellknownthat(CB(X)jH)isametricspaceandif(Xjd)iscom-
plete,then(CB(X)jH)isalsocomplete
Lemma1([9]).IfAjBCB(X)andk>1,thenforeachaA,there
existsbBsuchthatd(ajb)kH(AjB).
Letf:XXbeasingle-valuedmappingandT:XCB(X)bea
multi-valuedmapping.
Definition1.1)ApointxXissaidtobeacoincidencepointoff
andTiffxTx.WedenotebyC(fjT)thesetofallcoincidencepoints
offandT.
2)ApointxXisafixedpointofTifxTx.