Afr. Mat.
DOI 10.1007/s13370-016-0467-3
A note on partial metric type structures and metric type
structures
Maggie Aphane
1
· Seithuti Moshokoa
1
Received: 29 April 2016 / Accepted: 14 October 2016
© African Mathematical Union and Springer-Verlag Berlin Heidelberg 2016
Abstract In the note we discuss partial metric type structures and present their basic prop-
erties as well as their relationship with metric type structures. As an application, fixed point
theorems for a Lipschitzian map on this structures will be presented.
Keywords Partial metric space · Partial cone metric space · Cauchy complete · 0-Cauchy
complete
Mathematics Subject Classification 54A05 · 40A05 · 47H10
1 Basic notions and preliminaries
In the sequel the letter N will denote the set of positive integers. In this section we recall
some well known notions, definitions and results that will be used through out the paper.
A subset P of a real Banach space E is called a cone if,
(i) P is closed, nonempty and P ={0};
(ii) if for a, b ∈ R, a, b ≥ 0 and x , y ∈ P, then ax + by ∈ P ;
(iii) if for both a ∈ P and −a ∈ P, then a = 0.
Given a cone P in E a partial ordering ≤ on E via P is defined by a ≤ b if and only if
b − a ∈ P for a, b ∈ E . We write a < b to indicate that a ≤ b but a = b while a << b
will stand for b − a ∈ int ( P ), where int ( P ), denotes the interior of P in the norm topology
of E . The cone P in E is called normal if there exists a constant M > 0 such that for all
a, b ∈ E , 0 ≤ a ≤ b implies ||a|| ≤ M||b||.
B Seithuti Moshokoa
MoshokoaSP@tut.ac.za
Maggie Aphane
AphaneM@tut.ac.za
1
Department of Mathematics and Statistics, Tshwane University of Technology, Pretoria 0008, South
Africa
123