Derivation da of ordered -semirings · M.M.KrishnaRao,K.R.Kumar,B.Venkateswarlu,B.R.Kumar 119...

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doi: 10.5937/MatMor1802117M Mathematica Moravica Vol. 22, No. 2 (2018), 117–130 Derivation d a , β of ordered Γ-semirings Marapureddy Murali Krishna Rao, Kona Rajendr Kumar, Bolineni Venkateswarlu, Bandaru Ravi Kumar Abstract. In this paper, we introduce the concept of derivation d a,β of ordered Γ-semiring. We study some of the properties of derivation d a,β of ordered Γ-semirings. We prove that if a derivation d a,β is nonzero on an integral Γ-semiring M then it is non-zero on any non-zero ideal of M and we characterize k-ideal and m - k ideal using derivation d a,β of ordered Γ-semiring. 1. Introduction In 1995, Murali Krishna Rao [12, 13, 16] introduced the notion of Γ- semir- ing as a generalization of Γ- ring, ternary semiring and semiring. Semiring is an algebraic structure as, a common generalization of ring and distributive lattice.Semiring was first introduced by American mathematician Vandiver [19] in 1934 but non trivial examples of semirings had appeared in the earlier studies on the theory of commutative ideals of rings by German mathemati- cian Richard Dedekind in 19th century. Semiring is a universal algebra with two associative binary operations called addition and multiplication where one of them is distributive over the other. Bounded distributive lattices are commutative semirings which are both additively idempotent and mul- tiplicatively idempotent. A natural example of semiring is the set of all natural numbers under usual addition and multiplication of numbers. In particular, if I is the unit interval on the real line then (I, max, min), in which 0 is the additive identity and 1 is the multiplicative identity, is a semiring. The theory of rings and the theory of semigroups have consider- able impact on the development of the theory of semirings. Additive and multiplicative structures of a semiring play an important role in determining the structure of a semiring. Semirings are used in the areas of theoretical computer science as well as in the solutions of graph theory and optimization theory and in particular for studying automata, coding theory and formal 2000 Mathematics Subject Classification. 16Y60, 06F35, 08A30, 03G25. Key words and phrases. Derivation, Γ-semiring, ordered Γ-semiring, integral ordered Γ-semiring. Full paper. Received 19 April 2018, revised 17 May 2018, accepted 24 May 2018, available online 15 December 2018. c 2018 Mathematica Moravica 117

Transcript of Derivation da of ordered -semirings · M.M.KrishnaRao,K.R.Kumar,B.Venkateswarlu,B.R.Kumar 119...

Page 1: Derivation da of ordered -semirings · M.M.KrishnaRao,K.R.Kumar,B.Venkateswarlu,B.R.Kumar 119 Definition 2.2. A semiring M is called an ordered semiring if it admits a compatible

doi: 10.5937/MatMor1802117MMathematica MoravicaVol. 22, No. 2 (2018), 117–130

Derivation da,β of ordered Γ-semirings

Marapureddy Murali Krishna Rao, Kona Rajendr Kumar,Bolineni Venkateswarlu, Bandaru Ravi Kumar

Abstract. In this paper, we introduce the concept of derivation da,β ofordered Γ-semiring. We study some of the properties of derivation da,βof ordered Γ-semirings. We prove that if a derivation da,β is nonzero onan integral Γ-semiring M then it is non-zero on any non-zero ideal ofM and we characterize k-ideal and m− k ideal using derivation da,β ofordered Γ-semiring.

1. Introduction

In 1995, Murali Krishna Rao [12, 13, 16] introduced the notion of Γ- semir-ing as a generalization of Γ- ring, ternary semiring and semiring. Semiring isan algebraic structure as, a common generalization of ring and distributivelattice.Semiring was first introduced by American mathematician Vandiver[19] in 1934 but non trivial examples of semirings had appeared in the earlierstudies on the theory of commutative ideals of rings by German mathemati-cian Richard Dedekind in 19th century. Semiring is a universal algebra withtwo associative binary operations called addition and multiplication whereone of them is distributive over the other. Bounded distributive latticesare commutative semirings which are both additively idempotent and mul-tiplicatively idempotent. A natural example of semiring is the set of allnatural numbers under usual addition and multiplication of numbers. Inparticular, if I is the unit interval on the real line then (I,max,min), inwhich 0 is the additive identity and 1 is the multiplicative identity, is asemiring. The theory of rings and the theory of semigroups have consider-able impact on the development of the theory of semirings. Additive andmultiplicative structures of a semiring play an important role in determiningthe structure of a semiring. Semirings are used in the areas of theoreticalcomputer science as well as in the solutions of graph theory and optimizationtheory and in particular for studying automata, coding theory and formal

2000 Mathematics Subject Classification. 16Y60, 06F35, 08A30, 03G25.Key words and phrases. Derivation, Γ-semiring, ordered Γ-semiring, integral ordered

Γ-semiring.Full paper. Received 19 April 2018, revised 17 May 2018, accepted 24 May 2018,

available online 15 December 2018.

c©2018 Mathematica Moravica117

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118 Derivation da,β of ordered Γ-semirings

languages as the basic algebraic structure [6, 7]. Semiring theory has manyapplications in other branches [3, 4].

The notion of Γ−ring was introduced by Nobusawa [10] as a generaliza-tion of ring in 1964. Sen [18] introduced the notion of Γ− semigroup in1981. The notion of ternary algebraic system was introduced by Lehmer [8]in 1932. Lister [9] introduced the notion of ternary ring. Dutta & Kar in-troduced the notion of ternary semiring which is a generalization of ternaryring and semiring. After the paper [12] was published, many mathematiciansobtained interesting results on Γ-semirings.

Over the last few decades several authors have investigated the relation-ship between the commutativity of ring R and the existence of certain spec-ified derivations of R. The first result in this direction is due to Posner [11]in 1957. In the year 1990, Bresar and Vukman [2] established that a primering must be a commutative if it admits a non zero left derivation. Thenotion of derivation of ring is useful for characterization of rings [1, 17, 5].Murali Krishna Rao and Venkateswarlu [14, 15] introduced the concept ofgeneralized right derivation of Γ−incline and the concept of right derivationof ordered Γ-semirings. In this paper, we introduce the concept of derivationda,β of ordered Γ-semirings. We study some of the properties of derivationda,β of ordered Γ-semirings and we prove that if a derivation da,β is non-zeroon an integral ordered Γ-semiring M , then it is non-zero on any non-zeroideal of M .

2. Preliminaries

In this section we will recall some of the fundamental concepts and defi-nitions necessary for this paper.

Definition 2.1. Let (M,+) and (Γ,+) be commutative semigroups. Thenwe call M as a Γ−semiring,if there exists a mapping M × Γ ×M → M iswritten (x, α, y) as xαy such that it satisfies the following axioms

(i) xα(y + z) = xαy + xαz,(ii) (x+ y)αz = xαz + yαz,(iii) x(α+ β)y = xαy + xβy,(iv) xα(yβz) = (xαy)βz, for all x, y, z ∈M and α, β ∈ Γ.Every semiring R is a Γ−semiring with Γ = R and ternary operation xγy

as the usual semiring multiplication.We illustrate the definition of Γ−semiring by the following example

Example 2.1. Let S be a semiring andMp,q(S) denote the additive abeliansemigroup of all p× q matrices with identity element whose entries are fromS. Then Mp,q(S) is a Γ−semiring with Γ = Mp,q(S) ternary operation isdefined by xαz = x(αt)z as the usual matrix multiplication, where αt denotethe transpose of the matrix α; for all x, y and α ∈Mp,q(S).

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M. M. Krishna Rao, K.R. Kumar, B. Venkateswarlu, B.R. Kumar 119

Definition 2.2. A Γ−semiring M is called an ordered Γ−semiring if itadmits a compatible relation ≤ . i.e.≤ is a partial ordering on M satisfiesthe following conditions. If a ≤ b and c ≤ d then

(i) a+ c ≤ b+ d,(ii) aαc ≤ bαd,(iii) cαa ≤ dαb, for all a, b, c, d ∈M,α ∈ Γ.

Definition 2.3. A non-empty subset A of ordered Γ−semiring M is calleda Γ−subsemiring M if (A,+) is a subsemigroup of (M,+) and aαb ∈ A forall a, b ∈ A and α ∈ Γ.

Definition 2.4. A non-empty subset A of an ordered Γ−semiring. M iscalled a left (right) ideal of ordered Γ−semiringM if A satisfies the followingconditions.

(i) A is closed under addition,(ii) MΓA ⊆ A (AΓM ⊆ A),(iii) if for any a ∈M, b ∈A, a ≤ b implies a ∈A.

A is called an ideal of M if it is both a left ideal and a right ideal of M.

Definition 2.5. A non-empty subset A of an ordered Γ−semiring M iscalled a k−ideal if A is an ideal and x ∈M, x+ y ∈ A, y ∈ A then x ∈ A.

Definition 2.6. An ordered Γ−semiring M is said to have zero element ifthere exists an element 0 ∈ M such that 0 + x = x = x + 0 and 0αx =xα0 = 0, for all x ∈M,α ∈ Γ.

Definition 2.7. An element 1 ∈ M is said to be unity if for each x ∈ Mthere exists α ∈ Γ such that xα1 = 1αx = x.

Definition 2.8. An element a ∈ M is said to be idempotent of M if thereexists α ∈ Γ such that a = aαa and a is also said to be α idempotent.

Definition 2.9. A semigroup (M,+) is said to be band if a+a = a, for all a ∈M.

Definition 2.10. Every element of an ordered Γ−semiring M is an idem-potent of M then M is said to be idempotent ordered Γ−semiring M.

Definition 2.11. A non zero element a in an ordered Γ−semiringM is saidto be zero divisor if there exits non zero element b ∈ M,α ∈ Γ such thataαb = bαa = 0.

Definition 2.12. An ordered Γ−semiring M with unity 1 and zero element0 is called an integral ordered Γ−semiring if it has no zero divisors.

Definition 2.13. An ordered Γ−semiring M is said to be totally orderedΓ−semiring M if any two elements of M are comparable.

Definition 2.14. In an ordered Γ−semiring M

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120 Derivation da,β of ordered Γ-semirings

(i) the semigroup (M,+) is said to be positively ordered , if a ≤ a + band b ≤ a+ b, for all a, b ∈M.

(ii) the semigroup (M,+) is said to be negatively ordered, if a + b ≤ aand a+ b ≤ b, for all a, b ∈M.

(iii) the Γ−semigroup M is said to be positively ordered, if a ≤ aαb andb ≤ aαb, for all α ∈ Γ, a, b ∈M.

(iv) Γ−semigroup M is said to be negatively ordered if aαb ≤ a andaαb ≤ b for all α ∈ Γ, a, b ∈M.

Definition 2.15. Let M and N be ordered Γ− semirings. A mappingf : M → N is called a homomorphism if

(i) f(a+ b) = f(a) + f(b),(ii) f(aαb) = f(a)αf(b), for all a, b ∈M,α ∈ Γ.

Definition 2.16. Let M be an ordered Γ-semiring. A mapping d : M →Mis called a derivation if it satisfies the following conditions.

(i) d(x+ y) = d(x) + d(y),(ii) d(xαy) = d(x)αy + xαd(y) for all x, y ∈M and α ∈ Γ.

3. Derivation da,β of ordered Γ-semirings

In this section, we introduce the notion of derivation of the form da,β ofordered Γ-semirings. We study some of the properties of derivation da,β ofordered Γ-semirings.

Definition 3.1. Let M be an ordered Γ-semiring. Then for any a ∈M andβ ∈ Γ, we define a mapping d : M →M by d(x) = xβa, for all x ∈M .Thisfunction d is denoted by da,β .

Definition 3.2. Let M be an ordered Γ-semiring and da,β be a function.Then da,β is said to be derivation of M if

(i) da,β(x+ y) = da,β(x) + da,β(y),(ii) da,β(xαy) = da,β(x)αy + xαda,β(y), for all x, y ∈M,α ∈ Γ.

Example 3.1. Let M = {0, a, b, 1} and Γ = {α, β}. If we define the theadditive operations on M and Γ, by

+ 0 a b 10 0 a b 1a a a b 1b b b b 11 1 1 1 1

+ α βα α ββ β α

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M. M. Krishna Rao, K.R. Kumar, B. Venkateswarlu, B.R. Kumar 121

ternary operation, byα 0 a b 10 0 a b 1a a a b 1b b b b 11 1 1 1 1

β 0 a b 10 0 a b 1a a a b 1b b b b 11 1 1 1 1

and x ≤ y if and only if x + y = y, for all x, y ∈ M then M is an orderedΓ−semiring .

Let a ∈M and β ∈ Γ. Define da,β = xβa, for all x ∈M.Obviously da,β is a derivation of M

Example 3.2. LetM = [0, 1] and Γ = set of all natural numbers. Define thebinary operations + on M and Γ,by a+ b = max{a, b}, α+ β = max{α, β},and ternary operation by aαb = min{a, α, b}, for all a, b ∈M , α ∈ Γand a ≤ b if and only if a + b = b, for all a, b ∈ M.α, β ∈ Γ Then M is anordered Γ−semiring .

Let a ∈M and β ∈ Γ. Define da,β(x) = xβa, for all x ∈M.Obviously da,β is a derivation of M.

Theorem 3.1. LetM be an ordered commutative Γ-semiring in which semi-group (M,+) is a band .Then da,β is a derivation of M.

Proof. Let M be an ordered commutative Γ-semiring in which semigroup(M,+) is a band , x, y ∈M and α, β ∈ Γ. Then

da,β(xαy) = (xαy)βa

da,β(x)αy + xαda,β(y) = (xβa)αy + xαyβa

= yα(xβa) + xαyβa

= (yαx)βa+ xαyβa

= xαyβa+ xαyβa

= xαyβa.

Hence da,β is a derivation of M. �

Theorem 3.2. LetM be an ordered commutative Γ-semiring in which semi-group (M,+) is a band with unity element 1. Then for each x ∈ M ,thereexists a derivation d1,β , β ∈ Γ such that d1,β(x) = x.

Proof. Let x ∈M . Then there exists β ∈ Γ such that xβ1 = x. By Theorem3.1 d1,β is a derivation and d1,β(x) = xβ1 = x �

Theorem 3.3. Let M be an ordered Γ-semiring in which semigroup (M,+)is is a band and positively ordered, Γ-semigroup M is negatively ordered andda,β be a derivation.Then

(i) da,β(xαy) ≤ da,β(x) + da,β(y),(ii) da,β(x) ≤ x,

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122 Derivation da,β of ordered Γ-semirings

(iii) if x ≤ y then da,β(xαy) ≤ y.Proof. (i) Let x, y ∈M,α ∈ Γ then

da,β(xαy) = (xαy)βa

= (x+ x)αyβa

= xαyβa+ xαyβa

≤ xβa+ yβa

= da,β(x) + da,β(y).

(ii) da,β(x) = xβa ≤ x.(iii) Suppose x ≤ y. Then

x+ y ≤ y + y,

x+ y ≤ y ≤ x+ y,

x+ y = y.

da,β(xαy) ≤ da,β(x) + da,β(y)

≤ x+ y = y.

This completes the proof. �

Theorem 3.4. Let da,β be a derivation of an ordered Γ-semiring M .Then da,β(0) = 0.

Proof. By Definition 3.1, da,β(x) = xβa, for all x ∈ M. Then da,β(0) =0βa = 0.

Therefore da,β(0) = 0. �

Theorem 3.5. Let da,β be a derivation of an idempotent ordered Γ−semiringM in which Γ−semigroup M is negatively ordered , semigroup (M,+) is aband.Then da,β(x) ≤ x, for all x ∈M.

Proof. Let da,β be a derivation of an idempotent ordered Γ−semiring M inwhich Γ−semigroup M is negatively ordered. Suppose x ∈ M . Then thereexists α ∈ Γ such that xαx = x.

da,β(x) = da,β(xαx)

= da,β(x)αx+ xαda,β(x)

≤ x+ x.

Therefore da,β(x) ≤ x.This completes the proof. �

Theorem 3.6. Let M be an ordered Γ−semiring in which Γ−semigroup Mis negatively ordered. Then da,β(xαy) ≤ da,β(x+ y), for all x, y ∈M,α ∈ Γ.

Proof. Let M be an ordered Γ−semiring in which Γ−semigroup M is nega-tively ordered. Suppose x, y ∈M,α ∈ Γ. Then

da,β(x)αy ≤ da,β(x), xαda,β(y) ≤ da,β(y).

Page 7: Derivation da of ordered -semirings · M.M.KrishnaRao,K.R.Kumar,B.Venkateswarlu,B.R.Kumar 119 Definition 2.2. A semiring M is called an ordered semiring if it admits a compatible

M. M. Krishna Rao, K.R. Kumar, B. Venkateswarlu, B.R. Kumar 123

Therefore

da,β(xαy) = da,β(x)αy + xαda,β(y)

≤ da,β(x) + da,β(y)

= da,β(x+ y).

This completes the proof. �

Theorem 3.7. Let M be an idempotent ordered Γ-semiring in which Γ-semigroup M is negatively ordered and semigroup (M,+) is a band. Thenthe following hold for all x, y ∈M,α ∈ Γ.

(i) da,β(xαy) ≤ da,β(x) + da,β(y),(ii) If x ≤ y then da,β(xαy) ≤ da,β(y),(iii) da,β(x) ≤ x.

Proof. (i) The following holds

da,β(xαy) = da,β(x)αy + xαda,β(y)

≤ da,β(x) + da,β(y).

(ii) Suppose x ≤ y, thenxαda,β(y) ≤ yαda,β(y) ≤ y,da,β(x)αy ≤ y,da,β(xαy) = da,β(x)αy + xαda,β(y)

≤ y + y = y.

(iii) Let x ∈M. Then there exists α ∈ Γ such that xαx = x.

da,β(x) = da,β(xαx)

= da,β(x)αx+ xαda,β(x)

≤ x+ x = x.

This completes the proof. �

Theorem 3.8. Let M be an idempotent ordered Γ-semiring with unity 1 inwhich semigroup (M,+) is a band and positively ordered, Γ-semigroup M isnegatively ordered and da,β be a derivation of M. Then the following hold forall x ∈M ,

(i) xαda,β(1) ≤ da,β(x), α ∈ Γ,(ii) If da,β(1) = 1 then da,β(x) = x, for all x ∈M.

Proof. (i) Let x ∈M. Then there exists α ∈ Γ such that xα1 = x.Therefore

da,β(xα1) = da,β(x),

da,β(x)α1 + xαda,β(1) = da,β(x),

xαda,β(1) ≤ da,β(x).

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124 Derivation da,β of ordered Γ-semirings

(ii) Suppose da,β(1) = 1. We have

xαda,β(1) ≤ da,β(x),

xα1 ≤ da,β(x).

Therefore x ≤ da,β(x).By Theorem 3.7 , da,β(x) ≤ x. Hence da,β(x) = x, for all x ∈M. �

Theorem 3.9. Let M be an ordered Γ-semiring with unity 1 in which semi-group (M,+) is is a band and positively ordered, Γ-semigroupM is negativelyordered and da,β be a derivation of M. If x ∈M then there exists α ∈ Γ suchthat

(i) xαda,β(1) ≤ da,β(x),(ii) If da,β(1) = 1 then x ≤ da,β(x).

Proof. (i) LetM be an ordered Γ−semiring with unity 1, da,β be a derivationof M and x ∈M. Then there exists α ∈ Γ such that xα1 = x.

da,β(x) = da,β(xα1)

= da,β(x)α1 + xαda,β(1),

xαda,β(1) ≤ da,β(x)α1 + xαda,β(1) = da,β(x).

(ii) Suppose da,β(1) = 1 and xαda,β(1) ≤ da,β(x). Then ⇒ xα1 ≤ da,β(x)and x ≤ da,β(x).

This completes the proof. �

Theorem 3.10. Let M be an idempotent ordered Γ−semiring in whichΓ−semigroup M is negatively ordered and semigroup (M,+) is a band. Ifd2a,β(x) = da,β(da,β(x)) = da,β(x) then da,β(xαda,β(x)) ≤ da,β(x), for allx ∈M.

Proof. Let M be an idempotent ordered Γ−semiring and

d2a,β(x) = da,β(da,β(x)) = da,β(x),

for all x ∈M. Then

da,β(xαda,β(x)) = da,β(x)αda,β(x) + xαd(da,β(x))

= da,β(x) + xαda,β(x)

≤ da,β(x) + da,β(x)

= da,β(x).

Therefore da,β(xαda,β(x)) ≤ da,β(x).This completes the proof. �

Theorem 3.11. Let da,β be a derivation of an ordered integral-Γ-semiringM with unity and a ∈M . If aαda,β(x) = 0 for all x ∈M , α ∈ Γ then eithera = 0 or da,β = 0.

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M. M. Krishna Rao, K.R. Kumar, B. Venkateswarlu, B.R. Kumar 125

Proof. Suppose aαda,β(x) = 0, for all x ∈M , α ∈ Γ.Let y ∈M and γ ∈ Γ. If we replace x by xγy, then we obtain aαda,β(xγy) =

0 and

aα[da,β(x)γy + xβda,γ(y)] = 0,

aαxγda,β(y) = 0, γ ∈ Γ,

aα1γda,β(y) = 0,

aαda,β(y) = 0.

Therefore a = 0 or da,β(y) = 0 since M has no zero divisors.This completes the proof. �

Definition 3.3. An ideal I of an ordered Γ-semiring M is said to be m− kideal if xαy ∈ I , x ∈ I, 1 6= y ∈M and α ∈ Γ then y ∈ I.

Definition 3.4. Let da,β be a derivation of an ordered Γ-semiring M .Derivation da,β is called an isotone derivation if x ≤ y then da,β(x) ≤ da,β(y)for all x, y ∈M .

Theorem 3.12. Let da,β be an isotone derivation of an ordered Γ-semiringM . Define ker da,β = {x ∈M/da,β(x) = 0}. Then ker da,β is a k−ideal ofan ordered Γ-semiring M.

Proof. Let x, y ∈ ker da,β and α ∈ Γ. Then

xβa = yβa = 0,

da,β(x+ y) = (x+ y)βa = 0.

Therefore x+ y ∈ ker da,β.da,β(xαy) = da,β(x)αy + xαda,β(y)

= (xβa)αy + xα(yβa)

= 0αy + xα0 = 0.

Therefore xαy ∈ ker da,β .Suppose y ∈ ker da,β, x ∈M and x ≤ y. Then

da,β(x) ≤ da,β(y),

xβa ≤ yβa = 0,

xβa = 0,

x ∈ ker da,β.Hence ker da,β is an ideal.

Suppose x+ y ∈ ker da,β and y ∈ ker da,β . Thenda,β(x+ y) = 0,

da,β(x) + da,β(y) = 0,

da,β(x) = 0,

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126 Derivation da,β of ordered Γ-semirings

x ∈ ker da,β.This completes the proof. �

Theorem 3.13. Let da,β be an isotone derivation of an integral orderedΓ-semiring M . Then ker da,β is a m− k ideal of M.

Proof. By Theorem 3.12, ker da,β is an ideal of an ordered Γ-semiring M .Let 0 6= y ∈ ker da,β , x ∈M α ∈ Γ and xαy ∈ ker da,β. Then

da,β(xαy) = 0,

da,β(x)αy + xαda,β(y) = 0,

da,β(x)αy = 0,

da,β(x) = 0,

since M is an integral ordered Γ-semiring.Therefore ker da,β is a m− k ideal of M. �

Theorem 3.14. Let da,β be a derivation of multiplicatively cancellative com-mutative idempotent ordered Γ-semiring M where (M,+) is positively or-dered and band, Γ−semigroup M is negatively ordered and da,β(1) = 1.Define a set Fixda,β(M) = {x ∈ M | da,β(x) = x}. Then Fixda,β(M) is am− k ideal.

Proof. Obviously Fixda,β(M) = {x ∈ M/da,β(x) = x} is an ideal of M.Suppose xαy ∈ Fixda,β(M), x ∈ Fixda,β(M) and α ∈ Γ. Then

da,β(xαy) = xαy,

da,β(x)αy + xαda,β(y) = xαy,

xαy + xαda,β(y) = xαy,

xα[y + da,β(y)] = xαy,

y + da,β(y) = y,

da,β(y) ≤ y + da,β(y) = y.

By Theorem 3.9, we have y ≤ da,β(y). Hence da,β(y) = y, y ∈ Fixda,β(M).Therefore, Fixda,β(M) is a m− k−ideal of M. �

Theorem 3.15. Let M be an ordered commutative Γ-semiring and da,β,db,γ be derivations of M. If da,β db,γ = 0 then db,γ da,β is a derivation ofM.

Proof. Let x, y ∈M and α ∈ Γ. Then

0 = da,β db,γ (xαy)

= da,β[ db,γ (x)αy + xα db,γ (y)]

= da,β( db,γ (x))αy + db,γ (x)αda,β(y) + da,β(x)α db,γ (y) + xαda,β( db,γ (y)),

0 = db,γ (x)αda,β(y) + da,β(x)α db,γ (y).

Page 11: Derivation da of ordered -semirings · M.M.KrishnaRao,K.R.Kumar,B.Venkateswarlu,B.R.Kumar 119 Definition 2.2. A semiring M is called an ordered semiring if it admits a compatible

M. M. Krishna Rao, K.R. Kumar, B. Venkateswarlu, B.R. Kumar 127

db,γ da,β(x+ y) = db,γ [da,β(x) + da,β(y)]

= db,γ (da,β(x)) + db,γ (da,β(y))

and

db,γ da,β(xαy) = db,γ [da,β(x)αy + xαda,β(y)]

=db,γ da,β(x)αy + da,β(x)α db,γ (y) + db,γ (x)αda,β(y)

+ xα db,γ (da,β(y))

=db,γ (da,β(x))αy + xα db,γ (da,β(y)).

Hence db,γ da,β is a derivation of M. �

Theorem 3.16. Let da,β be a derivation of an ordered integral Γ-semiringM with unity and b ∈M,α ∈ Γ. Then if bαda,β(x) = 0, for all x ∈M,α ∈ Γ.Then either b = 0 or da,β is zero.

Proof. Suppose bαda,β(x) = 0, for all x ∈ M . Let y ∈ M . Replace x byxαy, then

bαda,β(xαy) = 0,

bα[da,β(x)αy + xαda,β(y)] = 0,

bαxαda,β(y) = 0, α ∈ Γ.

Since b ∈M , there exists γ ∈ Γ such that bγ1 = b, then

bγda,β(y) = 0,

b = 0 or da,β(y) = 0,

b = 0 or da,β = 0.

This completes the proof. �

Theorem 3.17. Let M be an ordered Γ-semiring in which (M,+) is posi-tively ordered and band,Γ−semigroup M is negatively ordered and da,β be aderivation of M . Then the following hold,

(i) da,β(xαy) ≤ da,β(x),(ii) da,β(xαy) ≤ da,β(y),(iii) x ≤ y then da,β(x) ≤ da,β(y), for all x, y ∈M,α ∈ Γ.

Proof. (i) Let x, y ∈M,α ∈ Γ. Then

da,β(xαy) = (xαy)βa ≤ xβa = da,β(x).

(ii) Similarly we can prove da,β(xαy) ≤ da,β(y).(iii) Suppose x ≤ y. Then

x+ y ≤ y + y,

x+ y ≤ y ≤ x+ y,

x+ y = y,

da,β(x+ y) = da,β(y),

Page 12: Derivation da of ordered -semirings · M.M.KrishnaRao,K.R.Kumar,B.Venkateswarlu,B.R.Kumar 119 Definition 2.2. A semiring M is called an ordered semiring if it admits a compatible

128 Derivation da,β of ordered Γ-semirings

da,β(x) + da,β(y) = da,β(y).

Therefore da,β(x) ≤ da,β(y). �

Theorem 3.18. Let da,β be a derivation of an integral ordered Γ-semiringM in which semigroup (M,+) is a band. Define d2a,β(x) = da,β(da,β(x)), forall x ∈M. If d2a,β = 0 then da,β = 0.

Proof. Let x, y ∈M and α ∈ Γ. Then

d2a,β(xαy) = 0,

da,β[da,β(xαy)] = 0,

da,β[da,β(x)αy + xαda,β(y)] = 0,

d2a,β(x)αy + da,β(x)αda,β(y) + da,β(x)αda,β(y) + xαd2a,β(y) = 0,

da,β(x)αda,β(y) + da,β(x)αda,β(y) = 0,

da,β(x)αda,β(y) = 0,

da,β(x) = 0 or da,β(y) = 0,

for all x, y ∈M . Therefore in both the cases we have da,β = 0.This completes the proof. �

Theorem 3.19. Let I be a non-zero ideal of an integral ordered Γ-semiringM in which Γ−semigroup M is negatively ordered. If da,β is a non-zeroderivation of M then da,β is non-zero on I.

Proof. Suppose da,β is a non-zero derivation of M and da,β(x) = 0 for allx ∈ I. Let y ∈M,α ∈ Γ and x ∈ I. Then xαy ≤ x. Therefore xαy ∈ I, and

da,β(xαy) = 0,

da,β(x)αy + xαda,β(y) = 0,

xαda,β(y) = 0.

Since M has no zero divisors, we have x = 0 or da,β(y) = 0, for all y ∈M.Further, since I is a non-zero ideal, we get da,β(y) = 0, for all y ∈ M,

which is a contradiction to da,β 6= 0 on M. Hence da,β is non-zero derivationon I.

This completes the proof. �

Theorem 3.20. Let da,β be a non-zero derivation of an integral ordered Γ-semiring M. If I is a non-zero ideal of M and t ∈M such that tαda,β(I) = 0then t = 0.

Proof. By Theorem 3.19, there exists x ∈ I such that da,β(x) 6= 0.Suppose tαda,β(I) = 0. Then

tαda,β(xαx) = 0,

tα[da,β(x)αx+ xαda,β(x)] = 0,

Page 13: Derivation da of ordered -semirings · M.M.KrishnaRao,K.R.Kumar,B.Venkateswarlu,B.R.Kumar 119 Definition 2.2. A semiring M is called an ordered semiring if it admits a compatible

M. M. Krishna Rao, K.R. Kumar, B. Venkateswarlu, B.R. Kumar 129

tαda,β(x)αx+ tα(xαda,β(x)) = 0,

tα(xαda,β(x)) = 0.

Therefore t = 0.This completes the proof. �

4. Conclusion

In this paper, we introduced the concept of derivation da,β of orderedΓ-semiring. We studied some of the properties of derivation da,β of orderedΓ-semirings. We proved that if a derivation da,β is non-zero on an integralΓ-semiring M , then it is non-zero on any non-zero ideal of M and we char-acterized k-ideal and m−k ideal using derivation da,β of ordered Γ-semiring.

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Marapureddy Murali Krishna RaoDepartment of MathematicsGIT, GITAM UniversityVisakhapatnam – 530 045IndiaE-mail address: [email protected]

Kona Rajendr KumarDepartment of MathematicsGIT, GITAM UniversityVisakhapatnam – 530 045IndiaE-mail address: [email protected]

Bolineni VenkateswarluDepartment of MathematicsGST, GITAM UniversityDoddaballapura – 561 203Bengaluru rualIndiaE-mail address: [email protected]

Bandaru Ravi KumarDepartment of MathematicsGST, GITAM UniversityMedak District – 502329HyderbadIndiaE-mail address: [email protected]