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Abstract
In p-hemiregular hemirings, some properties of ‘prime fuzzy p-ideals’ are examined. In the case of fuzzy p-ideal, p-hemiregular hemiring is also characterised. It is showed that in the case of hemiring , fuzzy subset φ is a ‘prime fuzzy left p-ideal’ in
if and only if φ is having two values, set having all values of in
so that φ(p) equals to one is a ‘prime left(right) p-ideal’ in
, φ(0) = 1. In hemirings for ‘maximal fuzzy left(right) p-ideals’, some related properties are also studied.
1 Introduction
Classical mathematics cannot be strongly used to solve complex problems in environmental sciences, social sciences, engineering, economics etc. due to different uncertainties in above-mentioned fields. So, among different changes in mathematics and sciences, one of the biggest changes in this century is the introduction of the concept of uncertainty. This change in science is visible by the development of the traditional view to alternative view, where according to the traditional view, uncertainty is annoying in science and it should be escaped straight out. On the other hand, according to the alternative view, we cannot avoid uncertainty and it should be considered also science should work for certainty in all its materialisations. Thus, uncertainty is considered as unscientific which shows that uncertainty is not only necessary but it has a great usage and is crucial for science according to the modern or alternative view. The first step of evolution from the traditional view to alternative view of uncertainty has been started at the end of the nineteenth century, when physics got bothered with mechanisms at the molecular level. Basically, the demand to study physical mechanisms at the molecular level in different way lead to the evolution of related statistical methods which brought out applications not only in the study of molecular mechanisms but also in the other fields like the actuarial profession, design of large telephone exchanges etc. Fuzzy sets were firstly introduced by Zadeh [Citation1], which are sets with bounds that are not explicit. In this type of sets, membership is not an entity of confirmation rather it is an entity of degree. The importance of his paper is that he not only claimed probability theory as the solitary operator for uncertainty but also to the basics of probability theory. The evolution from membership to membership and vice versa expressed by fuzzy sets has a great usage. It not only tells us effective ways of measuring uncertainties but also by using it we can express the uncertain notions in natural language. Fuzzy set theory greatly fascinated mathematicians working in different areas of mathematics like group theory, topology, vector spaces, functional analysis etc. So they worked a lot to prolong the results and concepts of algebra to fuzzy set theory. An extension to these results and concept of fuzzy sets applied in algebra is discussed in detail by the authors in [Citation2–6]. In different fields such as generalised fuzzy algebra, the usage of rings and semirings has been sufficiently studied in the literature. In algebraic research to realise the importance of rings, the work of many great and leading algebraists in this area is sufficient. Some of them who proved some useful results are [Citation6–19]. When we apply the theory of rings to random semirings, much of the theory of rings work. Much progress is done in generalizing the theory of semirings to ring theory by many other analysts. Since the fast progress in computer science was longing for abstract mathematical grounding. So in the 1980s, in computer science, semiring theory added a lot. Semirings contributed largely in providing reasonable generalisation of ring theory. Above all, the theory of algebras over commutative rings can be derived in every respect to the theory of algebras over commutative semirings. We also recognise the importance of ideals in algebra specifically in rings. In the structural theory of semirings, ideals play a vital role and therefore have great usage for a number of purposes. Yet, their usage is rather reserved in demanding to get correlations of semiring theorems for rings because they generally do not synchronise to ideals in rings. Of course, in the case of ideals in rings, there are many results which probably have no correlations with semirings. As ideals are of much importance in mathematics, therefore they are also studied at large scale by different mathematicians such as [Citation20] who not only studied properties of ideals in detail but also suggested the basic concepts of ideals, translation ideals and maximal ideals. They are also studied thoroughly by [Citation21, Citation22]. To some degree, there are many results in semirings which are not interconnected using ideals; so, correspondingly, there are many modified notions of ideals like k-ideals, h-ideals, p-ideals etc. which semiring theory recommends. Furthermore, the theory which was profitable in algebra to conclude many vital concepts was fuzzy set theory taken up by Zadeh [Citation1]. Many scholars have worked on fuzzy set theory in semirings and made known the notions of ‘fuzzy semirings’, ‘fuzzy ideals’, ‘fuzzy k-ideals’, ‘fuzzy h-ideals’ and ‘L-fuzzy ideals’ in semirings and got so many useful results. Touqeer et al. gave the concept of α-ideals and different decision making techniques [Citation23–28]. Ghosh [Citation12, Citation29] made known the concepts of ‘fuzzy k-ideals’, ‘prime fuzzy k-ideals’ and ‘semiregularity of semirings’. ‘Fuzzy k-ideals’ which are idempotent in semirings are portrayed by Mordeson [Citation30]. Moreover, he also explained thoroughly k-regular semirings in the form of ‘fuzzy left k- ideals’. Further ‘k-ideals’ were more comprehensively studied by [Citation31–36].
2 Preliminaries
A hemiring (, +,) refers to a non-empty set H with ‘+’ and ‘ ’ as the two binary operations defined on ϱ such that it is an additively commutative semiring with additive identity. About rings, semirings and basic ideals in these algebras, one can see [Citation20,Citation21,Citation27,Citation37].
Definition 2.1
If be any left ideal in H then it is called left k-ideal in H if q, r ∈ , p ∈ further p + q = r shows that p ∈ . Right k-ideals can be defined in a similar way.
Definition 2.2
If be any left ideal in then it is said to be left h-ideal in
so that (∀ p, r ∈
)(∀ , ∈ )(p + + r = + r) implies p . Right h-ideals can be defined in a similar manner. From now onwards,
will denote hemiring unless otherwise specified.
3 Fuzzy p-ideals
Definition 3.1
For any non-empty set of X which is left ideal is called left p-ideal when (p · r) · (q · r), q ∈ and p, r ∈ then
implies p ∈ ..
Definition 3.2
In hemiring , a fuzzy left p-ideal can be defined as ϱ which is fuzzy left ideal so that
implies ϱ(p) min ϱ((p r) (q r)), ϱ(q). Fuzzy right p-ideals can be defined in a similar way.
Definition 3.3
p-product of ϱ and p can be defined as
4 p-hemiregularity
Definition 4.1
is said to be p-hemiregular if for every ∈
∃ , ∈
so that
Definition 4.2
In when (p · r) · (q · r), q ∈ and p, r ∈
, p-closure of can be defined as
Lemma 4.3
Let
then for
must be equal to
Proof As contain in
and
contain in
then clearly
contain in
and through upon
contain in
. For the proof of converse inclusion p contains in
and q contains in
then in
, so that
and
by putting
by
and
Hence, we can derive pq
as
and
, which shows that pq
for any p
, q
. Now suppose randomly
. Then
for any
and
, therefore
, i.e.
; hence,
so clearly
.
Lemma 4.4
For right and left p-ideal and
respectively of
,
.
Lemma 4.5
For any right left p-ideals , respectively,
iff
is semi regular.
Proof Let ∈ and
be p-hemiregular then for every ∈
∃, c ∈
so that
because is right p-ideal in
we will have (i · ci)· (i · ci) ∈ and (i · ci) · (i · ci) ∈ .
Therefore, then by 4.4 clearly
.
Conversely, assume that ∈ so as we know it is easy to prove
+
for
= {0, 1, 2, … } be the principle right ideal in
which is generated by . As a result,
is a right p-ideal in
thus
as
itself is p-ideal trivially. Therefore
clearly
whence
As
are right and left p-ideals in
respectively. This follows that for every
so that
therefore
is a p-hemiregular hemiring.
Theorem 4.6
= ϱ ∩ Xi when ϱ be ‘fuzzy right p-ideal’ and Xi be ‘fuzzy left p-ideal’ if and only if
be p-hemiregular.
Proof
Assume that be any p-hemiregular hemiring then
= ϱ ⊆ Xi by Lemma 2.7 for some ∈
∃, c ∈ so that
Thus
therefore
hence
. Conversely, suppose and are right and left p-ideals, respectively, in
. So, as we know, it is easy to analyse characteristic functions of
which are
to be ‘fuzzy right p-ideal’ and ‘fuzzy left p-ideal’, respectively.
5 Normal Fuzzy Left p-ideals
Definition 5.1
In , ‘normal fuzzy left p-ideal’ can be defined as ϱ which is fuzzy left p-ideal if there is any p ∈
so that ϱ(p) equals to one.
Proposition 5.2
In a hemiring , there is given any fuzzy left p-ideal ϱ, suppose ϱ+ be a fuzzy set of
defined as ϱ+(p) = ϱ(p) + 1 − ϱ(0)∀p ∈
. Then ϱ+ be a normal fuzzy left p-ideal in
which consists of ϱ.
Proof We have ϱ+(0) = ϱ(0) + 1 − ϱ(0) = 1 and
∀ p, q ∈ . Correspondingly
whence ϱ+ is a fuzzy left ideal in H. Suppose (p · r) · (q · r), q, p, r ∈
so that
then
Hence, clearly ϱ ⊆ ϱ+ and ϱ+ be a normal fuzzy left p-ideal in .
Corollary 5.3
Suppose ϱ and ϱ+ are as in 5.2. Let if there exists p∈ so that ϱ+(p) = 0 then ϱ(p) = 0.
Proof For any left p- ideal in , clearly χ is a normal fuzzy left p-ideal in
. It is so clear ϱ+ = ϱ iff ϱ be a ‘normal fuzzy left p-ideal’ in
.
Theorem 5.4
In a hemiring, suppose ϱ be a ‘fuzzy left p-ideal’ and suppose f: [0, ϱ(0) →[0, 1] is any increasing function. Fuzzy set ϱf: → [0, 1] defined as ϱf (p) = f (ϱ(p)) be a fuzzy left p-ideal in . Particularly ϱf is normal if f (ϱ(0)) = 1 only when so that ϱ ⊆ ϱf.
Proof Clearly, we have
, ∀p, q ∈
. Correspondingly
Therefore, ϱf be a fuzzy left ideal in
. If for any (p · r) · (q · r), q, p, r ∈
are so then
then
Hence, ϱf be a fuzzy left p-ideal in . Then clearly ϱ is normal if f (ϱ(0)) = 1. Suppose f (l) = f (ϱ(p)) ≥ ϱ(p) for p ∈
which clearly proves ϱ ⊆ ϱf.
Theorem 5.5
Suppose ϱ∈ be variable if it is a maximal element in (
,⊆). So ϱ will take just two values that are 0 and 1.
Proof. We have ϱ(0) = 1, as ϱ is normal. Suppose ϱ(p) /= 1 for any p ∈ . We claim ϱ(p) = 0. If not then ∃ p° ∈ so that 0 < ϱ(p°) < 1. A fuzzy set Xi defined on
putting Xi(p) =
then it is obvious that Xi is well defined and we will have
, ∀ p, q ∈
. Hence, Xi be a ‘fuzzy left p-ideal’ in
. Xi+ be a ‘maximal fuzzy left p-ideal’ in
by 5.2. Note that
and
Therefore,
is variable and ϱ is no more a maximal element in
, which is clearly a contradiction.
6 Prime Fuzzy Left p-ideals
Definition 6.1
In , φ is called ‘prime fuzzy left(right) p-ideal’ if φ is variable function and for any ϱ and Xi to be two fuzzy left(right) p-ideals in
,
⊆ φ which shows that ϱ ⊆ φ or Xi ⊆ φ.
Theorem 6.2
A fuzzy subset φ is a ‘prime fuzzy left(right) p-ideal’ in if and only if (i)
= {p ∈
|φ(p) = φ(0)}be a prime left(right) p-ideal in
(ii) ℑ(φ) = {φ(p)|p ∈
} consists of two elements exactly. (iii) φ(0) must be equal to one.
Proof. This theorem will just be proved for left p-ideals. Because right p-ideals can be proved similarly. It is simple to evaluate as a ‘prime left p-ideal’. Let us consider ℑ(φ) has more than two values. Then there must exist two elements (p · r) · (q · r), q ∈
\
so that φ((p · r) · (q · r)) /= φ(q) without having loss in generality we may suppose that φ((p · r) · (q · r)) < φ(q). As φ is a fuzzy left p-ideal and q does not contains in
. It shows that φ((p · r) · (q · r)) < φ(q) < φ(0) therefore ∃r, l ∈ [0, 1] then
(1)
(1)
Suppose Xi and ω are fuzzy left p-ideals so that we can define them as Xi =
and
where
be characteristic function of ideals which are generated by (p · r) · (q · r) and q, respectively. Then, for each p ∈
which cannot be expressed by the form (p1 · p2) + ((p1 · r1) · (q1 · r1)) · q1 + r1 · r2 = ((p2 · r2) · (q2 · r2)) · q2 + r1 · r2, where r ∈
, (p1 · r1) · (q1 · r1), (p2 · r2) · (q2 · r2) ∈ 〈(p · r) · (q · r)〉 and q1, q2 ∈ 〈q〉 we will have on
the other hand
As φ is a ‘fuzzy left p-ideal’ from
it shows that
So hence
⊆ φ which shows Xi ⊆ φ or ω ⊆ φ as φ is a fuzzy prime left p-ideal. Hence,
or
clearly which contradicts to 1. As a resul,t ℑ (ϱ) exactly consists of two elements. To verify (iii), let φ be a ‘prime fuzzy left p-ideal’ and φ(0) must be not equal to one. So by (ii),
for
. As
, we have φ(0)=κ2
Therefore
Let for fixed (p · r) · (q · r) ∈ φ° and q ∈
\ φ° be two fuzzy subsets
for . Clearly, ϱ and Xi be fuzzy left p-ideals in
. If p is not able to satisfy the equality
for (p1 · r1) · (q1 · r1), (p2 · r2) · (q2 · r2) ∈ 〈(p · r) · (q · r)〉, q1, q2 ∈ 〈q〉 and r ∈
then on the other hand
By (i),
is a ‘prime left p-ideal’. Let ((p1 ·r1)·(q1 ·r1)), ((p2 ·r2)·(q2 ·r2)) ∈
〈(p·r)·(q ·r)〉 then ((p1 · r1) · (q1 · r1)), ((p2 · r2) · (q2 · r2)) ∈
because (p · r)· (q · r) ∈
and 〈(p · r)· (q · r)〉 ⊆
.
This shows that p ∈ therefore
thus
. But
and
which implies ϱ
φ and Xi
φ. Which contradicts the given assumption which is φ is a ‘prime fuzzy left p-ideal’ in
. Thus, φ(0) is equal to one. Conversely, the above-mentioned conditions are supposed to satisfy. Then φ(0) = 1 and ℑ (ϱ) = {κ, 1} for any
Further
for some p, q ∈
as φ(p + q) < min{φ(p), φ(q)} shows φ(p) = φ(q) = 1 that is p, q ∈
hence p + q ∈
and as a result φ(p + q) = 1 which cannot be possible. Correspondingly, φ(pq) ≥ φ(q) as φ(q) = 1 shows that pq ∈
hence φ(pq) = 1. Which shows that φ is a ‘fuzzy left ideal’ in
. In fact, φ be a ‘fuzzy left p-ideal’. It is clearly prime. Of course, if there are two fuzzy left p-ideals
so that
then
and for
any
. It is possible only if
=
= κ, i.e.
∈/
as
is prime then there must exists r ∈
so that
otherwise
whence
. So,
because φˆ is a left p-ideal in
. Furthermore,
by 4.3. Therefore,
and as a result
or
. In the first case,
hence
, thus
for
which is a clearly contradiction. The second case also gives contradiction.
Suppose then
as a result of assumption
(2)
(2)
Clearly
Therefore
for some
thus for
we will have
As
and
this contradicts 2. Therefore, for any fuzzy left p-ideals ϱ and Xi in
shows ϱ ⊆ φ or Xi ⊆ ζ, which clearly completes our proof.
7 Conclusion
The work done on fuzzy sets in semirings and hemirings must be connected in future with building a fuzzy spectrum in hemirings and in examining semiprime fuzzy p-ideals. In this paper, we examined the fact that key results in semirings related to fuzzy sets are similar but not the same as that of the corresponding results in hemirings. So, fuzzy sets of different types must be studied in rings, semirings and hemirings. The results which we obtained in this paper can be consumed to examine the graph that whether it is balanced or clusterable and also to examine social network problems.
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No potential conflict of interest was reported by the author(s).
Additional information
Notes on contributors
Muhammad Touqeer
Muhammad Touqeer did his PhD from University of Punjab, Lahore in 2015 and is currently working as Assistant Professor of Mathematics in the Department of Basic Sciences, University of Engineering and Technology Taxila, Pakistan. His field of interest includes Fuzzy sets, Soft sets, Fuzzy decision making and BCK/BCI algebras.
Atiqa Maryam
Atiqa Maryam did his MS-Mathematics from University of Engineering and Technology Taxila, Pakistan in 2019 and is currently working as Lecturer (Visiting) in Mathematics Department, University of Education Jauhrabad, Pakistan. Her field of interest is Fuzzy Algebra.
Muhammad Nauman Saeed
Muhammad Nauman Saeed did his MS- Mathematics from University of Engineering and Technology Taxila, Pakistan in 2019 and is currently working as SESE-Mathematics in Govt. High School Verowal, Pakistan. His field of interest includes Fuzzy sets, Soft sets, Fuzzy soft set decision making problems.
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