
generalised to bitopological spaces, as well as
separation axioms, connectedness, function types,
and more concepts. In 1982, [2], demonstrated that
the lindelöf property is maintained by counter
images of closed mappings using lindelöf
counter images for points. He introduced a new type
of mapping, called closed mappings, that are
strictly weaker than closed mappings. Also, he
demonstrated that if the inverse image of every
point in the range is paracompact with respect to the
domain (lindelöf, respectively), then the
paracompactness (strongly paracompactness)
property is maintained by obtaining counter images
of closed mappings using regular domains.
Moreover, he defined space as a generalisation
of space and demonstrated that for any
space , the projection of is
closed if and only if is in a lindelöf space.
Additionally, he derived various product theorems
related to lindelöf for paracompact and strongly
paracompact spaces using spaces. He then
discusses a few different examples that relate to the
definitions and theorems that are provided. In 2021,
in, [3], introduces pairwise perfect functions as
well as pairwise perfect functions,
describing their features and searching for
homeomorphisms between various bitopological
spaces under their influence. Finally, he provides
the product theorem characterizations. In 2022, [4],
presented the idea of weakly continuous
functions within bitopological spaces as a
generalisation of continuous functions, and
they obtained numerous features and some of their
characteristics. Also, in the same year 2022, [5],
proposed the idea of nearly continuous
functions within bitopological spaces as a
generalization of continuous functions, and
they established several results and some of their
characteristics. While, in 2022, [6], created a new
type of function via open sets that he named
rarely continuous function and examined many
characteristics of this function. Throughout this
research, we will use paircompact, which refers to
pairwise compact and pair to denotes pairwise. If
represents a bitopological space and
; then the closure for with regard to and ,
respectively, will be indicated by the symbols
and . Let be a subset of and let
be any topological space, a point
is known as the condensation point of
if is uncountable set, for any with
. The following describes the way, [7], described
closed sets as well as open sets. If A has all
its condensation points, it is said to as closed.
open is the complement of a closed set.
Additionally, the intersection with all closed
sets that contain will be indicated by .
Also, the space , or just refers to any
bitopological space on which, unless otherwise
specified, no separation axioms can be taken for
assumed in this resaerch. Paircontinuous
functions are a new kind of weakened continuous
function that is introduced in this study.
Additionally, we define pairbarely continuous
functions, a new, weakened type of barely
continuous functions. First, in Section 3, we
establish numerous characteristics of
paircontinuous functions. Several examples
are provided in Section 4 to show how
paircontinuous functions and certain
weakened forms of pairwise continuous functions
are connected. In the end, we show whether a
pairω-continuous image that represents a
pairlindelöf space is also a pairlindelöf space in
Section 5 by presenting a new, basic
characterization of pairlindelöf spaces.
Furthermore, as demonstrated in Section 5, a
pairwise only barely continuous image is
hereditarily. Applications of continuous functions
with different topological spaces can be found in
[8], [9], [10], [11], [12], [13], [14], [15], [16], [17],
[18], [19], [20], [21], [22], [23], [24], [25], [26],
[27], [28], [29].
2 Preliminaries
This section presents some significant concepts
along with specifics are covered that used within the
research.
Definition 2.1, [2] A function
is said to be paircontinuous if the
functions and
are continuous.
Definition 2.2, [2] A function
is said to be pairclosed if the functions
and are
closed.
Definition 2.3, [2] Let be any
bitopological space. Then, a cover of the space
is called open if .
Moreover, is called pairopen if has at least
one-nonempty member of .
Definition 2.4, [2] Let be any
bitopological space. Then, the space is called
WSEAS TRANSACTIONS on MATHEMATICS
DOI: 10.37394/23206.2023.22.105
Ali A. Atoom, Hamza Qoqazeh,
Rahmeh Alrababah, Eman Almuhur,
Nabeela Abu-Alkishik