Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6, 9544-9554 2024 Publisher: Learning Gate DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate ยฉ 2024 by the authors; licensee Learning Gate * Correspondence: gregoria.ariyanti@ukwms.ac.id Notes on matrix inverse over min-plus algebra Gregoria Ariyanti1*, Ana Easti Rahayu Maya Sari2, Christina Manurung3 1,2,3Department of Mathematics Education, Widya Mandala Surabaya Catholic University; gregoria.ariyanti@ukwms.ac.id (G.A.) Abstract: One of the semiring structures is the max-plus algebra, a set with entries โ„๐œ€ = โ„ โˆช {โˆ’โˆž} equipped with the operation โŠ•, which represents the maximum value, and the operation โŠ—, which means addition. Another semiring structure is the min-plus algebra, a set with entries โ„๐œ€ = โ„ โˆช {+โˆž} equipped with the operation โŠ•, representing the minimum value, and the operation โŠ—, which means addition. Matrices over min-plus algebras can have inverses determined by certain conditions. The general inverse type can define the inverse of matrices over min-plus algebras. In this paper, we will develop the characteristics of general inverse matrices over min-plus algebras. The research method used is the literature study method sourced from books and journal articles. The main result of this study is that the generalized inverse of the matrix ๐ด โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘› can be obtained by determining the matrix ๐‘‹ with entry ๐‘‹๐‘˜๐‘™ = ๐‘› ๐‘š๐‘–๐‘› ๐‘– = 1 ๐‘› ๐‘š๐‘–๐‘› ๐‘— = 1 (โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘Ž๐‘–๐‘— โˆ’ ๐‘Ž๐‘™๐‘—) which satisfies ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด. Keywords: Generalized, Inverse, Min-plus algebra. 1. Introduction Semiring is an algebraic structure obtained from rings with the condition that a ring is weakened by eliminating several ring conditions. Other algebraic structures known as Semigroups and Semirings will emerge if some properties of Groups and Rings are weakened. This shows that the algebraic structures created are Semigroups and then Semirings if some Group or Ring conditions are removed ([1], [2]). The main difference between semiring and ring structures can be seen from the existence of an inverse element for the addition operation ([3], [4]). A structure (S,+,ร—) with S, a non-empty set, + addition operation, and ร— multiplication operation, is semiring if it fulfils the commutative and associative properties of addition, multiplication associativity, distributive, has a zero element, and a unit element ([4], [5]). It is well known that a semigroup is formed by a non-empty set S and the associative binary operation ร—. Thus, the structure (S,+,ร—) is said to be semiring if (S,+) is a commutative semigroup, (S,ร—) is a semigroup, distributive, has element 0 and has a unit element ([6], [7]). With semiring entries, a semiring matrix can be developed [1], [5], [8]. One structure that is a semiring is max-plus algebra. A structure (โ„max,โŠ•,โŠ—) with โ„max = โ„ โˆช {โˆ’โˆž} is said to be a max-plus algebra with a maximum โŠ• operation and an addition โŠ— operation. In another section, a semiring other than max-plus algebra is min-plus algebra. Min-plus algebra Rmin = R โˆช {+โˆž} with minimum (โŠ• โ€ฒ) and addition (โŠ—) operations with identity elements with respect to โŠ• โ€ฒ are ๐œ€โ€ฒ = +โˆž and ๐‘’ = 0. Max-plus algebra and min-plus algebra are isomorphic because of their similar structure. It is possible to convert the idea of max-plus algebra into min-plus algebra [5]. The semiring element has an inverse to the addition operation so that the determinant of a matrix over the semiring can be defined ([3], [6]). The inverse of the semiring matrix can be determined by determining the determinant of the semiring matrix. Looking at the characteristics of the semiring, we will specifically look at the characteristics of min-plus algebra. It is done because not all semiring properties also apply to min-plus algebra. As with Group and Ring structures, the commutative characteristic applies to certain Semirings [6], [9], [10]. A particular Semiring owns the existence of an inverse element for addition on a Semiring. In 9545 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 9544-9554, 2024 DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate a semiring, the entry on the semiring has the inverse of the + operation so that the determinant of the matrix on the semiring can be defined. This study aims to develop the characteristics of the generalized inverse matrix over a min-plus algebra. 2. Materials and Methods Reducing several properties will form a new algebraic structure. Not all properties of the complete structure will also be reduced to the new algebraic structure. The research uses a literature study method sourced from books and journal articles. The steps for developing ideas in this study are shown in Figure 1. Figure 1. Procedure for the characteristic study of min-plus algebra. 2.1. Min-Plus Algebra The properties of a max-plus algebra can be used to create a min-plus algebra. Definition 1 The structure (โ„๐‘š๐‘–๐‘›,โŠ•โ€ฒ,โŠ—) is said to be a min-plus algebra with โ„๐‘š๐‘–๐‘› = โ„ โˆช {+โˆž}, the binary operations โŠ• โ€ฒ and โŠ— defined as ๐‘Ž โŠ• โ€ฒ ๐‘ = ๐‘š๐‘–๐‘› {๐‘Ž, ๐‘} and ๐‘Ž โŠ— ๐‘ = ๐‘Ž + ๐‘ for ๐‘Ž, ๐‘ โˆˆ โ„๐‘š๐‘–๐‘›. Theorem 1 provides the algebraic property of min-plus. Theorem 1 For an ๐‘ฅ, ๐‘ฆ, ๐‘ง โˆˆ โ„๐‘š๐‘–๐‘› with ๐‘’ โ‰” 0 and ๐œ€โ€ฒ = +โˆž applies 1. Associative, namely โˆ€๐‘ฅ, ๐‘ฆ, ๐‘ง โˆˆ โ„๐‘š๐‘–๐‘› , ๐‘ฅ โŠ•โ€ฒ (๐‘ฆ โŠ•โ€ฒ ๐‘ง) = (๐‘ฅ โŠ•โ€ฒ ๐‘ฆ) โŠ• โ€ฒ๐‘ง and ๐‘ฅ โŠ— (๐‘ฆ โŠ— ๐‘ง) = (๐‘ฅ โŠ— ๐‘ฆ) โŠ— ๐‘ง 2. Commutative, namely โˆ€๐‘ฅ, ๐‘ฆ โˆˆ โ„๐‘š๐‘–๐‘›, ๐‘ฅ โŠ• โ€ฒ๐‘ฆ = ๐‘ฆ โŠ• โ€ฒ๐‘ฅ and ๐‘ฅ โŠ— ๐‘ฆ = ๐‘ฆ โŠ— ๐‘ฅ 3. Distributive of โŠ— over โŠ• โ€ฒ, namely โˆ€๐‘ฅ, ๐‘ฆ, ๐‘ฅ โˆˆ โ„๐‘š๐‘–๐‘›,๐‘ฅ โŠ— (๐‘ฆ โŠ•โ€ฒ ๐‘ง) = (๐‘ฅ โŠ— ๐‘ฆ) โŠ• โ€ฒ(๐‘ฅ โŠ— ๐‘ง) 4. There is a zero element, namely โˆ€๐‘ฅ โˆˆ โ„๐‘š๐‘–๐‘›, ๐‘ฅ โŠ• โ€ฒ๐œ€ = ๐œ€ โŠ• โ€ฒ๐‘ฅ = ๐‘ฅ 5. There is a unit element, namely โˆ€๐‘ฅ โˆˆ โ„๐‘š๐‘–๐‘›, ๐‘ฅ โŠ— ๐‘’ = ๐‘’ โŠ— ๐‘ฅ = ๐‘ฅ 6. There is an absorption property by the zero element ๐œ€โ€ฒ towards โŠ—,that is โˆ€๐‘ฅ โˆˆ โ„๐‘š๐‘–๐‘›, ๐‘ฅ โŠ— ๐œ€โ€ฒ = ๐œ€โ€ฒ โŠ— ๐‘ฅ = ๐œ€โ€ฒ 7. The idempotent property of โŠ• โ€ฒ, namely โˆ€๐‘ฅ โˆˆ โ„๐‘š๐‘–๐‘›, ๐‘ฅ โŠ• โ€ฒ๐‘ฅ = ๐‘ฅ Meanwhile, defining the determinant uses permutation characteristics. The definition of permutation is given as follows. 9546 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 9544-9554, 2024 DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate Definition 2 A permutation matrix is a matrix with exactly one entry (๐‘’) and another entry (๐œ€โ€ฒ) in each of its ๐‘– โˆ’th row and ๐‘— โˆ’th column. The permutation matrix over the min-plus algebra can be described as ๐‘ƒ๐œŽ = [๐‘๐‘–๐‘—] with ๐‘๐‘–๐‘— = { ๐‘’; ๐‘– = ๐œŽ(๐‘—) ๐œ€โ€ฒ; ๐‘– โ‰  ๐œŽ(๐‘—) if ๐œŽ: {1, 2, โ€ฆ , ๐‘›} โŸถ {1, 2, โ€ฆ , ๐‘›} is a permutation. Thus, ๐‘’ appears in the ๐œŽ(๐‘— โˆ’ ๐‘กโ„Ž) row in the ๐‘— โˆ’th column of ๐‘ƒ๐œŽ. Example 1 Let ๐œŽ: {1, 2} โ†’ {1, 2} with ๐œŽ(1) = 2 and ๐œŽ(2) = 1, then ๐‘11 = { ๐‘’ ๐‘—๐‘–๐‘˜๐‘Ž 1 = ๐œŽ(1) ๐œ€โ€ฒ ๐‘—๐‘–๐‘˜๐‘Ž 1 โ‰  ๐œŽ(1) , ๐‘11 = ๐œ€โ€ฒ ๐‘12 = { ๐‘’ ๐‘—๐‘–๐‘˜๐‘Ž 1 = ๐œŽ(2) ๐œ€โ€ฒ ๐‘—๐‘–๐‘˜๐‘Ž 1 โ‰  ๐œŽ(2) , ๐‘12 = ๐‘’ ๐‘21 = { ๐‘’ ๐‘—๐‘–๐‘˜๐‘Ž 2 = ๐œŽ(1) ๐œ€โ€ฒ ๐‘—๐‘–๐‘˜๐‘Ž 2 โ‰  ๐œŽ(1) , ๐‘21 = ๐‘’ ๐‘21 = { ๐‘’ ๐‘—๐‘–๐‘˜๐‘Ž 2 = ๐œŽ(2) ๐œ€โ€ฒ ๐‘—๐‘–๐‘˜๐‘Ž 2 โ‰  ๐œŽ(2) , ๐‘22 = ๐œ€ โ€ฒ The permutation matrix is [๐œ€โ€ฒ ๐‘’ ๐‘’ ๐œ€โ€ฒ ]. Example 2 Let ๐ด = [ 1 3 โˆ’2 3 5 8 4 6 โˆ’1 ] , ๐‘ƒ๐œŽ = [ ๐œ€โ€ฒ ๐‘’ ๐œ€โ€ฒ ๐œ€โ€ฒ ๐œ€โ€ฒ ๐‘’ ๐‘’ ๐œ€โ€ฒ ๐œ€โ€ฒ ] we have ๐ด โŠ— ๐‘ƒ๐œŽ = [ 1 3 โˆ’2 3 5 8 4 6 โˆ’1 ] โŠ— [ ๐œ€โ€ฒ ๐‘’ ๐œ€โ€ฒ ๐œ€โ€ฒ ๐œ€โ€ฒ ๐‘’ ๐‘’ ๐œ€โ€ฒ ๐œ€โ€ฒ ] = [ โˆ’2 1 3 8 3 5 โˆ’1 4 6 ] The right-hand multiplication of ๐‘ƒ๐œŽ creates a permutation of the matrix columns so that the ๐‘– โˆ’th column of A appears as the ๐œŽ(๐‘–) โˆ’th column of ๐ด โŠ— ๐‘ƒ๐œŽ. The permutation matrix ๐‘ƒ๐œŽ has an inverse, namely ๐‘ƒ๐œŽโˆ’1 where ๐‘ƒ๐œŽโˆ’1 is the transpose of ๐‘ƒ๐œŽ obtained ๐‘ƒ๐œŽโˆ’1 = ๐‘ƒ๐œŽ๐‘‡ so that ๐‘ƒ๐œŽ โŠ— ๐‘ƒ๐œŽโˆ’1 = ๐ธ. If ๐ด is a matrix over a field, then a single matrix ๐ต must satisfy the property ๐ด โŠ— ๐ต โŠ— ๐ด = ๐ด. A matrix ๐ต that satisfies this property is called the generalized inverse of matrix ๐ด. In min-plus algebra, there is no guarantee that every matrix has a generalized inverse. If ๐ด has a generalized inverse, then ๐ด is considered regular. We will discuss determining whether a matrix ๐ด is a regular min-plus algebra. A min-plus algebra can be formed based on the characteristics of a max-plus algebra. As an initial characteristic, the following theorem is given. Theorem 2 Given an idempotent commutative semigroup (๐‘†, +). If on S a relation โ‰ฅ is defined by ๐‘ โ‰ฅ ๐‘Ž โŸบ ๐‘Ž + ๐‘ = ๐‘, then the relation โ‰ค is a partial order on S. Proof : Given any ๐‘Ž, ๐‘, ๐‘ โˆˆ ๐‘† then 1. Since S is idempotent, then ๐‘Ž + ๐‘Ž = ๐‘Ž โŸบ ๐‘Ž โ‰ฅ ๐‘Ž 9547 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 9544-9554, 2024 DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate 2. If ๐‘ โ‰ฅ ๐‘Ž and ๐‘Ž โ‰ฅ ๐‘, then ๐‘Ž + ๐‘ = ๐‘ and ๐‘ + ๐‘Ž = ๐‘Ž. Since ๐‘† is commutative, then ๐‘Ž = ๐‘ 3. If ๐‘ > ๐‘Ž and ๐‘Ž > ๐‘ then ๐‘Ž + ๐‘ = ๐‘ and ๐‘ + ๐‘Ž = ๐‘Ž then ๐‘ + ๐‘ = (๐‘Ž + ๐‘) + ๐‘ = (๐‘ + ๐‘Ž) + ๐‘ = ๐‘ + (๐‘Ž + ๐‘) = ๐‘ + ๐‘Ž = ๐‘ So, we have ๐‘ > ๐‘. Definition 3 In โ„๐‘š๐‘–๐‘› , the relation โ‰ฅ๐‘š๐‘–๐‘› is defined as ๐‘ฅ โ‰ฅ๐‘š๐‘–๐‘› ๐‘ฆ โŸบ ๐‘ฅ โŠ•โ€ฒ ๐‘ฆ = ๐‘ฆ Theorem 3 The relation โ‰ฅ๐‘š๐‘–๐‘› is a partial order. Proof: Given ๐‘Ž, ๐‘, ๐‘ โˆˆ โ„๐‘š๐‘–๐‘›, then 1. Since โ„๐‘š๐‘–๐‘› is idempotent then ๐‘Ž โŠ•โ€ฒ ๐‘Ž = min{๐‘Ž, ๐‘Ž} = ๐‘Ž therefore ๐‘Ž โ‰ฅ๐‘š๐‘–๐‘› ๐‘Ž 2. If ๐‘Ž โ‰ฅ๐‘š๐‘–๐‘› ๐‘ and ๐‘ โ‰ฅ๐‘š๐‘–๐‘› ๐‘Ž then ๐‘Ž โŠ• โ€ฒ๐‘ = ๐‘ and ๐‘ โŠ• โ€ฒ๐‘Ž = ๐‘Ž. Since โ„๐‘š๐‘–๐‘› is commutative then ๐‘Ž = ๐‘ 3. If ๐‘Ž โ‰ฅ๐‘š๐‘–๐‘› ๐‘ and ๐‘ โ‰ฅ๐‘š๐‘–๐‘› ๐‘ then ๐‘Ž โŠ•โ€ฒ ๐‘ = ๐‘ and ๐‘ โŠ•โ€ฒ ๐‘ = ๐‘ then ๐‘Ž โŠ•โ€ฒ ๐‘ = ๐‘Ž โŠ•โ€ฒ (๐‘ โŠ•โ€ฒ ๐‘) = ๐‘Ž โŠ•โ€ฒ (๐‘ โŠ•โ€ฒ ๐‘) = (๐‘Ž โŠ•โ€ฒ ๐‘) โŠ•โ€ฒ ๐‘ = ๐‘ โŠ•โ€ฒ ๐‘ = ๐‘ So, ๐‘Ž โ‰ฅ๐‘š๐‘–๐‘› ๐‘. Definition 4 For โ„๐‘š๐‘–๐‘›, we use the parsial ordered โ‰ฅ๐‘š๐‘–๐‘›, that is ๐‘Ž โ‰ฅ๐‘š๐‘–๐‘› ๐‘ โŸบ ๐‘Ž โŠ•โ€ฒ ๐‘ = min(๐‘Ž, ๐‘) = ๐‘. The structure (โ„๐‘š๐‘–๐‘› , โ‰ค) is a partially ordered set (poset). Theorem 4 Let ๐ด โˆˆ ๐‘€๐‘›(โ„๐‘š๐‘–๐‘›) and supposed ๐ฟ๐ด: โ„๐‘š๐‘–๐‘› ๐‘› โŸถ โ„๐‘š๐‘–๐‘› ๐‘› with ๐ฟ๐ด(๐‘ฅ) = ๐ด โŠ— ๐‘ฅ. We have ๐ด = ๐‘ƒ๐œŽ โŠ— ๐ท(๐œ†๐‘–) for a permutation and ๐œ†๐‘– > ๐œ€ if and only if ๐ฟ๐ด injective. Proof : (โŸน) ๐ฟ๐ด(๐‘ฅ) = ๐ฟ๐ด(๐‘ฅโ€ฒ) such as ๐ด โŠ— ๐‘ฅ = ๐ด โŠ— ๐‘ฅโ€ฒ so ๐‘ฅ = ๐‘ฅโ€ฒ. (โŸธ) It is known that ๐ฟ๐ด is injective. For each ๐‘– can be defined ๐น๐‘– = {๐‘—|๐‘Ž๐‘—๐‘– > ๐œ€} and ๐บ๐‘– = {๐‘—|๐‘Ž๐‘—๐‘˜ > ๐œ€, ๐‘˜ โ‰  ๐‘–}. We called ๐น๐‘– โІ ๐บ๐‘–; the contradiction assumes that ๐น๐‘– โІ ๐บ๐‘–. We will show a contradiction with injective ๐ฟ๐ด. Let ๐‘ฅ = [๐‘ฅ๐‘˜] with ๐‘ฅ๐‘˜ = { ๐‘’ ; ๐‘˜ โ‰  ๐‘– ๐œ€ ; ๐‘˜ = ๐‘– . Suppose ๐‘ = ๐ด โŠ— ๐‘ฅ = โจ‚ ๐‘Žโˆ—๐‘˜๐‘˜โ‰ ๐‘– with ๐‘Žโˆ—๐‘˜ defined the ๐‘˜ โˆ’th column of A. Suppose ๐‘— โˆˆ ๐น๐‘–, then ๐‘— โˆˆ ๐บ๐‘–. Its mean that ๐‘˜ โ‰  ๐‘– for ๐‘Ž๐‘—๐‘˜ > ๐œ€. In โ„๐‘š๐‘–๐‘›, we can complete the order relation โ‰ค, namely ๐‘Ž โ‰ค ๐‘ if and only if ๐‘Ž โŠ• โ€ฒ๐‘ = ๐‘Ž. So (โ„๐‘š๐‘–๐‘› , โ‰ค) is a poset (partially ordered set). Definition 5 A mapping f on a partially ordered set is said to be isotone if for ๐‘ฅ โ‰ค ๐‘ฆ the result is ๐‘“(๐‘ฅ) โ‰ค ๐‘“(๐‘ฆ). Example 3 Given ๐‘“:โ„๐‘š๐‘–๐‘› โŸถ โ„๐‘š๐‘–๐‘› with ๐‘“(๐‘ฅ) = ๐‘ฅ โŠ— โ€ฒ7 is an isotone mapping, namely for every ๐‘ฅ โ‰ค ๐‘ฆ results in ๐‘ฅ โˆ’ 7 โ‰ค ๐‘ฆ โˆ’ 7 results in ๐‘“(๐‘ฅ) โ‰ค ๐‘“(๐‘ฆ). Definition 6 Given (๐ธ,โ‰ค) is a poset and ๐ด โІ ๐ธ. 9548 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 9544-9554, 2024 DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate i) For ๐‘Ž โˆˆ ๐ด there is ๐‘ฅ โˆˆ ๐ด resulting in ๐‘Ž โ‰ค ๐‘ฅ so ๐‘Ž is called minimum ii) For ๐‘Ž โˆˆ ๐ด it is called the minimal element of A if there is ๐‘ฅ โˆˆ ๐ด with ๐‘Ž โ‰ค ๐‘ฅ then ๐‘Ž = ๐‘ฅ. Definition 7 An isotone mapping ๐‘“: ๐ท โŸถ ๐ธ with D, E poset is said to be a residual mapping if for all ๐‘ โˆˆ ๐ธ then {๐‘ฅ|๐‘ โ‰ค ๐‘“(๐‘ฅ)} has a minimum element denoted ๐‘“#(๐‘). The isotone mapping ๐‘“#: ๐ธ โŸถ ๐ท is called residual of f. Theorem 5 If ๐‘“: ๐ท โ†’ ๐ธ is a residualized mapping, then the equation ๐‘“(๐‘ฅ) = ๐‘ has a solution if and only if ๐‘“(๐‘“# (๐‘)) = ๐‘. Proof: (โ‡’) Given ๐‘“(๐‘ฅ) = ๐‘ has a solution, say ๐‘ฅ1. We get ๐‘“(๐‘ฅ1 ) = ๐‘. Since ๐‘“#(๐‘) is a minimal element in {๐‘ฅ|๐‘“(๐‘ฅ) โ‰ค ๐‘}, then ๐‘ฅ1 โ‰ค ๐‘“#(๐‘). Since ๐‘“ is isotone then ๐‘“(๐‘ฅ1 ) โ‰ค ๐‘“(๐‘“#(๐‘)), according to (*) ๐‘“(๐‘“#(๐‘)) โ‰ค ๐‘, consequently ๐‘ = ๐‘“(๐‘ฅ1 ) โ‰ค ๐‘“๐‘“# (๐‘) โ‰ค ๐‘, namely ๐‘“(๐‘“#(๐‘)) = ๐‘. (โ‡) Given ๐‘“(๐‘“^# (๐‘)) = ๐‘, then the equation ๐‘“(๐‘ฅ) = ๐‘ has a solution, namely ๐‘ฅ = ๐‘“# (๐‘). The function ๐‘“ is residualized, because ๐‘ฆ โˆˆ โ„๐‘š๐‘–๐‘› with {๐‘ฅ|๐‘ฆ โ‰ค ๐‘ฅ โŠ—โ€ฒ 7 = ๐‘“(๐‘ฅ)} is a minimal element, namely ๐‘ฅ = ๐‘“#(๐‘ฆ) = ๐‘ฆ + 7. Definition 8 For every ๐‘ โˆˆ ๐ธ then {๐‘ฅ|๐‘ โ‰ค ๐‘“(๐‘ฅ)} has a minimal element denoted ๐‘“#(๐‘). For ๐‘ฆ โˆˆ โ„๐‘š๐‘–๐‘› {๐‘ฅ|๐‘ฆ โ‰ค ๐‘ฅ โŠ—โ€ฒ 7 = ๐‘“(๐‘ฅ)} the minimal element is ๐‘ฅ = ๐‘“#(๐‘ฆ) = ๐‘ฆ + 7. Definition 9 A subsolution of ๐ด โŠ— ๐‘ฅ = ๐‘ is ๐‘ฅ that satisfies ๐ด โŠ— ๐‘ฅ โ‰ฅ ๐‘, a linear system for obtaining the general result of the equation ๐ด โŠ— ๐‘ฅ = ๐‘. An ordered pair of vectors is defined by ๐‘ฅ โ‰ฅ ๐‘ฆ if ๐‘ฅ โŠ•โ€ฒ ๐‘ฆ = ๐‘ฆ. Since ๐ด โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘› and ๐‘‹ โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘› then ๐ด โŠ— ๐‘ฅ = [ ๐‘Ž11 ๐‘Ž12 ๐‘Ž21 ๐‘Ž22 โ‹ฏ ๐‘Ž1๐‘› โ‹ฏ ๐‘Ž2๐‘› โ‹ฎ โ‹ฎ ๐‘Ž๐‘›1 ๐‘Ž๐‘›2 โ‹ฑ โ‹ฎ โ‹ฏ ๐‘Ž๐‘›๐‘› ] โŠ— [ ๐‘ฅ1 ๐‘ฅ2 โ‹ฎ ๐‘ฅ๐‘› ] = [ ๐‘Ž11 + ๐‘ฅ1 โŠ•โ€ฒ ๐‘Ž12 + ๐‘ฅ2 โŠ•โ€ฒ โ‹ฏโŠ•โ€ฒ ๐‘Ž1๐‘› + ๐‘ฅ๐‘› ๐‘Ž21 + ๐‘ฅ1 โŠ•โ€ฒ ๐‘Ž22 + ๐‘ฅ2 โŠ•โ€ฒ โ‹ฏโŠ•โ€ฒ ๐‘Ž2๐‘› + ๐‘ฅ๐‘› โ‹ฎ ๐‘Ž๐‘›1 + ๐‘ฅ1 โŠ•โ€ฒ ๐‘Ž๐‘›2 + ๐‘ฅ2 โŠ•โ€ฒ โ‹ฏโŠ•โ€ฒ ๐‘Ž๐‘›๐‘› + ๐‘ฅ๐‘› ] = [ โŠ• โ€ฒ๐‘Ž1๐‘— + ๐‘ฅ๐‘— โŠ• โ€ฒ๐‘Ž2๐‘— + ๐‘ฅ๐‘— โ‹ฎ โŠ• โ€ฒ๐‘Ž๐‘›๐‘— + ๐‘ฅ๐‘—] , ๐‘— = 1,2,โ€ฆ , ๐‘› with โŠ• โ€ฒ๐‘Ž1๐‘— + ๐‘ฅ๐‘— = ๐‘š๐‘–๐‘›{๐‘Ž11 + ๐‘ฅ1, ๐‘Ž12 + ๐‘ฅ2, โ‹ฏ , ๐‘Ž1๐‘› + ๐‘ฅ๐‘›} 9549 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 9544-9554, 2024 DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate Form ๐‘“๐‘—(๐‘ฅ๐‘—) = [ ๐‘Ž1๐‘— + ๐‘ฅ1 ๐‘Ž2๐‘— + ๐‘ฅ2 โ‹ฎ ๐‘Ž๐‘›๐‘— + ๐‘ฅ๐‘› ] so that ๐ด โŠ— ๐‘ฅ = ๐‘› โŠ•โ€ฒ ๐‘— = 1 ๐‘“๐‘—(๐‘ฅ๐‘—). So, ๐ด โŠ— ๐‘ฅ = ๐‘“1(๐‘ฅ1) โŠ•โ€ฒ ๐‘“2(๐‘ฅ2) โŠ•โ€ฒ โ‹ฏโŠ•โ€ฒ ๐‘“๐‘›(๐‘ฅ๐‘›). For each ๐‘—, if ๐‘ฅ๐‘—โ„Ž โ‰ค ๐‘ฅ๐‘—๐‘˜ โŸน ๐‘“๐‘—(๐‘ฅ๐‘—โ„Ž) โ‰ค ๐‘“๐‘—(๐‘ฅ๐‘—๐‘˜). According Definition 5 and Theorem 5, so {๐‘ฅ|๐ด โŠ— ๐‘ฅ โ‰ฅ ๐‘} has a minimum element denoted ๐ด#(๐‘). Therefore, to determine the solution of the equation ๐ด๐‘ฅ = ๐‘, check wether ๐ด (๐ด#(๐‘)) = ๐‘. The following is a theorem that states this characteristic. Theorem 6 If ๐ด โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘› and ๐‘ โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘› , then the equation ๐ด โŠ— ๐‘ฅ = ๐‘ has a solution if and only if ๐ด (๐ด#(๐‘)) = ๐‘. In other words, the solution is ๐‘ฅ = ๐ด#(๐‘). Proof : (โŸน) It is known that the equation ๐ด โŠ— ๐‘ฅ = ๐‘ has a solution ๐‘ฅโˆ—, namely ๐ด โŠ— ๐‘ฅโˆ— = ๐‘, so that ๐ด โŠ— ๐‘ฅโˆ— โ‰ฅ ๐‘. Since ๐ด#๐‘ is the minimal element in {๐‘ฅ|๐ด โŠ— ๐‘ฅ โ‰ฅ ๐‘}, then ๐‘ฅโˆ— โ‰ฅ ๐ด#๐‘. It is obtained ๐ด โŠ— ๐‘ฅโˆ— โ‰ค ๐ด(๐ด#๐‘) โŸบ ๐‘ = ๐ด โŠ— ๐‘ฅโˆ— โ‰ฅ ๐ด(๐ด#๐‘) โ€ฆโ€ฆโ€ฆ . . (โˆ—) Furthermore, according to Theorem 5 ๐ด(๐ด#๐‘) โ‰ฅ ๐‘ โ€ฆโ€ฆโ€ฆโ€ฆ (โˆ—โˆ—) From (โˆ—) and (โˆ—โˆ—) it is obtained ๐ด (๐ด#(๐‘)) = ๐‘. (โŸธ) It is known that ๐ด(๐ด#๐‘) = ๐‘. So the equation ๐ด โŠ— ๐‘ฅ = ๐‘ has a solution, namely ๐‘ฅ = ๐ด#๐‘. Therefore, ๐ด โŠ— ๐‘ฅ = ๐‘ has a solution ๐‘ฅ = ๐ด#(๐‘). It means that ๐ด (๐ด#(๐‘)) = ๐‘. For example, if ๐ด โŠ— ๐‘ฅ = ๐‘ has solution ๐‘ฅ๐‘—, then there is a smallest subsolution ๐ด โŠ— ๐‘ฅ = ๐‘. ๐ด โŠ— ๐‘ฅ โ‰ฅ ๐‘ โŸบ โŠ•โ€ฒ ๐‘— ๐ด๐‘–๐‘— โŠ— ๐‘ฅ๐‘— โ‰ฅ ๐‘๐‘–, โˆ€๐‘– then ๐ด๐‘–1 โŠ— ๐‘ฅ1 โŠ•โ€ฒ ๐ด๐‘–2 โŠ— ๐‘ฅ2 โŠ•โ€ฒ โ€ฆโŠ•โ€ฒ ๐ด๐‘–๐‘› โŠ— ๐‘ฅ๐‘› โ‰ฅ ๐‘๐‘– ๐‘– = 1 โŸน ๐ด11 โŠ— ๐‘ฅ1 โŠ•โ€ฒ ๐ด12 โŠ— ๐‘ฅ2 โŠ•โ€ฒ โ€ฆโŠ•โ€ฒ ๐ด1๐‘› โŠ— ๐‘ฅ๐‘› โ‰ฅ ๐‘1 ๐‘– = 2 โŸน ๐ด21 โŠ— ๐‘ฅ1 โŠ•โ€ฒ ๐ด22 โŠ— ๐‘ฅ2 โŠ•โ€ฒ โ€ฆโŠ•โ€ฒ ๐ด2๐‘› โŠ— ๐‘ฅ๐‘› โ‰ฅ ๐‘2 โ‹ฎ ๐‘– = ๐‘› โŸน ๐ด๐‘›1 โŠ— ๐‘ฅ1 โŠ•โ€ฒ ๐ด๐‘›2 โŠ— ๐‘ฅ2 โŠ•โ€ฒ โ€ฆโŠ•โ€ฒ ๐ด๐‘›๐‘› โŠ— ๐‘ฅ๐‘› โ‰ฅ ๐‘๐‘› for ๐‘–, min{๐ด๐‘–1 +๐‘ฅ1, ๐ด๐‘–2 + ๐‘ฅ2, โ€ฆ , ๐ด๐‘–๐‘› + ๐‘ฅ๐‘›} โ‰ฅ ๐‘๐‘–. For ๐‘–, ๐‘—, we have ๐ด๐‘–๐‘— + ๐‘ฅ๐‘— โ‰ฅ ๐‘๐‘– , which results in ๐‘ฅ๐‘— โ‰ฅ ๐‘๐‘– โˆ’ ๐ด๐‘–๐‘— . Obtain ๐‘ฅ๐‘— โ‰ฅ ๐‘š๐‘Ž๐‘ฅ{๐‘๐‘– โˆ’ ๐ด๐‘–๐‘—} for each ๐‘–. Next, โˆ’๐‘ฅ๐‘— โ‰ค ๐‘š๐‘–๐‘›{โˆ’๐‘๐‘– + ๐ด๐‘–๐‘—} for each ๐‘–. In other words โˆ’๐‘ฅ๐‘— โ‰ค ๐‘š๐‘–๐‘›{โˆ’๐‘๐‘– โŠ— ๐ด๐‘–๐‘—} for each ๐‘–. So that โˆ’๐‘ฅ๐‘— = ๐‘š๐‘–๐‘›{โˆ’๐‘๐‘– โŠ— ๐ด๐‘–๐‘—}subsolution of ๐ด โŠ— ๐‘ฅ = ๐‘ or expressed โˆ’๐‘ฅ๐‘— = ๐‘š๐‘–๐‘› {(๐ด๐‘–๐‘—) ๐‘ก โŠ— (โˆ’๐‘๐‘—)}. Example 4 Given a system of linear equations over min-plus algebra 9550 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 9544-9554, 2024 DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate [ 2 3 4 5 ] โŠ— [ ๐‘ฅ1 ๐‘ฅ2 ] = [ 6 7 ] We get โˆ’๐‘ฅ๐‘— = ๐‘š๐‘–๐‘›{โˆ’๐‘๐‘– โŠ— ๐ด๐‘–๐‘—} = [โˆ’6 โˆ’7] โŠ— [ 2 3 4 5 ] = [โˆ’4 โŠ•โ€ฒโˆ’ 3 โˆ’3 โŠ•โ€ฒโˆ’ 2] = [โˆ’4 โˆ’3] So, ๐‘ฅ๐‘— = [4 3]. Or, โˆ’๐‘ฅ๐‘— = ๐‘š๐‘–๐‘› {(๐ด๐‘–๐‘—) ๐‘ก โŠ— (โˆ’๐‘๐‘—)} = [ 2 4 3 5 ] โŠ— [ โˆ’6 โˆ’7 ] = [ โˆ’4 โŠ•โ€ฒโˆ’ 3 โˆ’3 โŠ•โ€ฒโˆ’ 2 ] = [ โˆ’4 3 ] It can be proven that [ 2 3 4 5 ] โŠ— [ ๐‘ฅ1 ๐‘ฅ2 ] = [ 2 3 4 5 ] โŠ— [ 4 3 ] = [ 6 โŠ•โ€ฒ 6 8 โŠ•โ€ฒ 8 ] = [ 6 8 ] โ‰ฅ [ 6 7 ] 3. Results and Discussion Based on the explanation above, the following properties are obtained. Definition 7 A matrix ๐ด โˆˆ ๐‘€๐‘›(๐‘…) is said to be invertible over the min-plus algebra if there is a matrix B such that ๐ด โŠ— ๐ต = ๐ธ with E the identity matrix over the min-plus algebra and is denoted ๐ต = ๐ดโŠ—โˆ’1 . To determine the inverse matrix over min-plus algebra, permutation is required. Definition 8 If ๐œ†1, ๐œ†2, โ€ฆ , ๐œ†๐‘› โˆˆ โ„๐‘š๐‘–๐‘›, ๐œ†๐‘– โ‰  ๐œ€ then the diagonal matrix is defined as follows. ๐ท(๐œ†๐‘–) = [ ๐œ†1 ๐œ€ ๐œ€ ๐œ†2 โ‹ฏ ๐œ€ โ‹ฎ ๐œ€ โ‹ฏ โ‹ฏ ๐œ€ ๐œ€ โ‹ฑ โ‹ฏ โ‹ฏ ๐œ†๐‘› ] Theorem 7 Given ๐ด โˆˆ ๐‘€๐‘›(๐‘…min). If and only if there is a permutation ๐œŽ and values ๐œ†๐‘– > ๐œ€, ๐‘– โˆˆ {1,2,โ€ฆ , ๐‘›} such that ๐ด = ๐‘ƒ๐œŽ โŠ— ๐ท(๐œ†๐‘–), then ๐ด โˆˆ ๐‘€๐‘›(๐‘…min) has a left inverse. Proof: (โŸน) Given ๐ด โˆˆ ๐‘€๐‘› (๐‘…๐‘š๐‘–๐‘›), there exist ๐ต so that it satisfies the equation ๐ด โŠ— ๐ต = ๐ธ, meaning (1) ๐‘š๐‘–๐‘›๐‘˜(๐‘Ž๐‘–๐‘˜ + ๐‘๐‘–๐‘˜) = ๐‘’ = 0 for every ๐‘˜ there is ๐‘– so that ๐‘Ž๐‘–๐‘˜ + ๐‘๐‘˜๐‘– = ๐‘’, we have the function ๐‘– = ๐œƒ(๐‘˜) with ๐‘Ž๐‘–๐œƒ(๐‘–) > ๐œ€ and ๐‘๐œƒ(๐‘–)๐‘– > ๐œ€. (2) ๐‘š๐‘–๐‘›๐‘˜(๐‘Ž๐‘–๐‘˜ + ๐‘๐‘˜๐‘—) = ๐œ€โ€ฒ = โˆž for all ๐‘– โ‰  ๐‘— Based on (2), it is obtained (3) ๐‘Ž๐‘–๐œƒ(๐‘—) = ๐œ€โ€ฒ for all ๐‘– โ‰  ๐‘—. Since ๐‘Ž๐‘–๐œƒ(๐‘–) > ๐œ€โ€ฒ = ๐‘Ž๐‘–๐œƒ(๐‘—) for all ๐‘– โ‰  ๐‘— then ๐œƒ is an injection and permutation function. Meanwhile, ๐‘Ž๐‘–๐œƒ(๐‘–) is a single entry in the ๐œƒ(๐‘–) โˆ’th column of ๐ด, which is not ๐œ€โ€ฒ. For example, ๏ฟฝฬ‚๏ฟฝ = ๐‘ƒ๐œƒ โŠ— ๐ด. The ๐œƒ(๐‘–) โˆ’th row of ๏ฟฝฬ‚๏ฟฝ is the ๐‘– โˆ’th row of ๐ด, which has a larger entry then ๐œ€โ€ฒ in the ๐œƒ(๐‘–) โˆ’th column. Thus, all larger ๏ฟฝฬ‚๏ฟฝ diagonal entries become ๐œ€โ€ฒ. A has only one nonโˆ’๐œ€โ€ฒ entry in each column, which is also true for ๏ฟฝฬ‚๏ฟฝ. 9551 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 9544-9554, 2024 DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate So we get ๐‘ƒ๐œƒ โŠ— ๐ด = ๏ฟฝฬ‚๏ฟฝ = ๐ท(๐œ†๐‘–) with ๐œ†๐‘– = ๐‘Ž๐œƒโˆ’1(๐‘–)๐‘– > ๐œ€โ€ฒ. Suppose, ๐œŽ = ๐œƒโˆ’1, because ๐‘ƒ๐œŽ โŠ— ๐‘ƒ๐œƒ = ๐‘ƒ๐œƒโˆ’1 โŠ— ๐‘ƒ๐œƒ = ๐ธ, then ๐ด = ๐‘ƒ๐œŽ โŠ— ๐ท(๐œ†๐‘–). So, it is proven that ๐ด = ๐‘ƒ๐œŽ โŠ— ๐ท(๐œ†๐‘–). (โŸธ) Assume ๐ด = ๐‘ƒ๐œŽ โŠ— ๐ท(๐œ†๐‘–) with ๐œ† โˆˆ ๐‘…๐‘š๐‘–๐‘› and ๐œ†๐‘– > ๐œ€. If the statement is true then for example ๐ต = ๐‘ƒ๐œŽโˆ’1 โŠ— ๐ท(โˆ’๐œ†๐‘–), with โˆ’๐œ†๐‘– = ๐œ†๐‘– โŠ—โˆ’1 . So we have ๐ด โŠ— ๐ต = (๐‘ƒ๐œŽ โŠ— ๐ท(๐œ†๐‘–)) โŠ— (๐‘ƒ๐œŽโˆ’1 โŠ— ๐ท(โˆ’๐œ†๐‘–)) = ๐‘ƒ๐œŽ โŠ— (๐ท(๐œ†๐‘–) โŠ— ๐ท(โˆ’๐œ†๐‘–)) โŠ— ๐‘ƒ๐œŽโˆ’1 = ๐‘ƒ๐œŽ โŠ— ๐ธ โŠ— ๐‘ƒ๐œŽโˆ’1 = ๐‘ƒ๐œŽ โŠ— ๐‘ƒ๐œŽโˆ’1 = ๐ธ And, ๐ด โŠ— ๐ต = ๐ธ and ๐ต is the right inverse of ๐ด. From the theorem above, we get the necessary and sufficient conditions for matrix A to be invertible over min-plus algebra, namely matrix A is invertible if and only if matrix A is a permuted diagonal matrix with ๐ด = ๐‘ƒ๐œŽ โŠ— ๐ท(๐œ†๐‘–). The purpose of finding the generalized inverse is to determine the solution of the linear equation system ๐ด๐‘‹๐ต = ๐ถ. A matrix ๐ด โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘› has a generalized inverse matrix ๐‘‹ โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘› if ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด. So, it can be said that the generalized inverse is the smallest subsolution of the equation ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด. Several steps are required to determine matrix ๐‘‹ as the generalized inverse of equation ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด. Definition 9 For a matrix ๐ด โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘›, then the matrix ๐ต โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘› is said to be the generalized inverse of the matrix A if ๐ด โŠ— ๐ต โŠ— ๐ด = ๐ด is satisfied. To determine whether or not there is a matrix ๐ต that satisfies ๐ด โŠ— ๐ต โŠ— ๐ด = ๐ด, is equivalent to determining whether or not there is a solution to the equation ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด with ๐ด โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘›. 1. Bring the equation ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด to the form ๐ด๐‘ฅ = ๐‘. 2. Determine the matrix ๐‘‹ 3. Prove that the matrix X is a generalized inverse by substituting it into the equation ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด. Given ๐ด โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘› with operations โŠ• โ€ฒ and โŠ—. The ๐‘–๐‘— โˆ’th element in ๐ด โŠ— ๐‘‹ โŠ— ๐ด with 1 โ‰ค ๐‘–, ๐‘— โ‰ค ๐‘› in ๐ด โŠ— ๐‘‹ โŠ— ๐ด is [๐ด โŠ— ๐‘‹ โŠ— ๐ด]๐‘–๐‘— = ๐ด๐‘–๐‘— โŸบ [๐ด โŠ— ๐‘‹]๐‘–๐‘™ โŠ— ๐ด๐‘™๐‘— = ๐ด๐‘–๐‘— 1 โ‰ค ๐‘™ โ‰ค ๐‘› โŸบ ๐ด๐‘–๐‘˜ โŠ— ๐‘‹๐‘˜๐‘™ โŠ— ๐ด๐‘™๐‘— = ๐ด๐‘–๐‘— 1 โ‰ค ๐‘˜, ๐‘™ โ‰ค ๐‘› โŸบ ๐ด๐‘–๐‘˜ โŠ— ๐‘› โŠ• โ€ฒ ๐‘™ = 1 ๐‘ฅ๐‘˜๐‘™ โŠ— ๐ด๐‘™๐‘— = ๐ด๐‘–๐‘— 1 โ‰ค ๐‘˜ โ‰ค ๐‘› โŸบ ๐‘› โŠ• โ€ฒ ๐‘˜ = 1 ๐ด๐‘–๐‘˜ โŠ— ๐‘› โŠ• โ€ฒ ๐‘™ = 1 ๐‘ฅ๐‘˜๐‘™ โŠ— ๐ด๐‘™๐‘— = ๐ด๐‘–๐‘— โŸบ ๐‘› โŠ• โ€ฒ ๐‘˜ = 1 ๐‘› โŠ• โ€ฒ ๐‘™ = 1 ๐ด๐‘–๐‘˜ โŠ— ๐‘ฅ๐‘˜๐‘™ โŠ— ๐ด๐‘™๐‘— = ๐ด๐‘–๐‘— 9552 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 9544-9554, 2024 DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate โŸบ ๐‘› โŠ•โ€ฒ ๐‘˜ = 1 [ ๐‘› โŠ•โ€ฒ ๐‘™ = 1 (๐ด๐‘–๐‘˜ โŠ— ๐‘‹๐‘˜๐‘™ โŠ— ๐ด๐‘™๐‘—)] = ๐ด๐‘–๐‘— So we get ๐‘› โŠ•โ€ฒ ๐‘– = 1 ๐‘› โŠ•โ€ฒ ๐‘— = 1 ๐‘“๐‘–๐‘—(๐‘‹๐‘˜๐‘™) = ๐ด๐‘–๐‘— . The generalized inverse can be found by solving the equation ๐ด โŠ— ๐‘ฅ = ๐‘ in min-plus algebra. For the generalized inverse, denoted ๐ดโŠ—โˆ’1, the form ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด is brought to the form ๐ด โŠ— ๐‘ฅ = ๐‘. For the ๐‘–๐‘— โˆ’th element, it is obtained as follows: โŸบ [๐ด โŠ— ๐‘‹ โŠ— ๐ด]๐‘–๐‘— = ๐ด๐‘–๐‘— โŸบ ๐ด๐‘–๐‘˜ โŠ— ๐‘‹๐‘˜๐‘™ โŠ— ๐ด๐‘™๐‘— = ๐ด๐‘–๐‘— โŸบ ๐ด๐‘–๐‘˜ โŠ— ๐‘‹๐‘˜๐‘™ โŠ— ๐ด๐‘™๐‘— โŠ— ๐ด๐‘™๐‘— โŠ—โˆ’1 = ๐ด๐‘–๐‘— โŠ— ๐ด๐‘™๐‘— โŠ—โˆ’1 โŸบ ๐ด๐‘–๐‘˜ โŠ— ๐‘‹๐‘˜๐‘™ โŠ— ๐ธ = ๐ด๐‘–๐‘— โˆ’ ๐ด๐‘™๐‘— If suppose ๐‘ = ๐ด๐‘–๐‘— โˆ’ ๐ด๐‘™๐‘— then we write โŸบ ๐ด๐‘–๐‘˜ โŠ— ๐‘‹๐‘˜๐‘™ = ๐‘ โŸบ ๐ธ โŠ— ๐‘‹๐‘˜๐‘™ = โˆ’๐ด๐‘–๐‘˜ โŠ— ๐‘ โŸบ ๐‘‹๐‘˜๐‘™ = โˆ’๐ด๐‘–๐‘˜ โŠ— ๐‘ โŸบ ๐‘‹๐‘˜๐‘™ = โˆ’[ ๐‘Ž11 ๐‘Ž12 ๐‘Ž21 ๐‘Ž22 โ‹ฏ ๐‘Ž1๐‘˜ โ‹ฏ ๐‘Ž2๐‘˜ โ‹ฎ โ‹ฎ ๐‘Ž๐‘–1 ๐‘Ž๐‘–1 โ‹ฑ โ‹ฎ โ‹ฏ ๐‘Ž๐‘–๐‘˜ ] โŠ— [ ๐‘11 ๐‘12 ๐‘21 ๐‘22 โ‹ฏ ๐‘1๐‘› โ‹ฏ ๐‘2๐‘› โ‹ฎ โ‹ฎ ๐‘๐‘›1 ๐‘๐‘›2 โ‹ฑ โ‹ฎ โ‹ฏ ๐‘๐‘›๐‘› ] โŸบ ๐‘‹๐‘˜๐‘™ = [ โˆ’๐‘Ž11 โˆ’๐‘Ž12 โˆ’๐‘Ž21 โˆ’๐‘Ž22 โ‹ฏ โˆ’๐‘Ž1๐‘˜ โ‹ฏ โˆ’๐‘Ž2๐‘˜ โ‹ฎ โ‹ฎ โˆ’๐‘Ž๐‘–1 โˆ’๐‘Ž๐‘–1 โ‹ฑ โ‹ฎ โ‹ฏ โˆ’๐‘Ž๐‘–๐‘˜ ] โŠ— [ ๐‘11 ๐‘12 ๐‘21 ๐‘22 โ‹ฏ ๐‘1๐‘› โ‹ฏ ๐‘2๐‘› โ‹ฎ โ‹ฎ ๐‘๐‘›1 ๐‘๐‘›2 โ‹ฑ โ‹ฎ โ‹ฏ ๐‘๐‘›๐‘› ] For ๐‘‹๐‘˜๐‘™ = [ ๐‘ฅ11 ๐‘ฅ12 ๐‘ฅ21 ๐‘ฅ22 โ‹ฏ ๐‘ฅ1๐‘™ โ‹ฏ ๐‘ฅ2๐‘™ โ‹ฎ โ‹ฎ ๐‘ฅ๐‘˜1 ๐‘ฅ๐‘˜2 โ‹ฑ โ‹ฎ โ‹ฏ ๐‘ฅ๐‘˜๐‘™ ] The result, ๐‘ฅ11 = min{โˆ’๐‘Ž11 + ๐‘11 , โˆ’๐‘Ž12 + ๐‘21, โ€ฆ , โˆ’๐‘Ž1๐‘˜ + ๐‘๐‘›1 } ๐‘ฅ12 = min{โˆ’๐‘Ž11 + ๐‘12 , โˆ’๐‘Ž12 + ๐‘22, โ€ฆ , โˆ’๐‘Ž1๐‘˜ + ๐‘๐‘›2 } โ‹ฎ ๐‘ฅ1๐‘™ = min{โˆ’๐‘Ž11 + ๐‘1๐‘› , โˆ’๐‘Ž12 + ๐‘2๐‘›, โ€ฆ , โˆ’๐‘Ž1๐‘˜ + ๐‘๐‘›๐‘› } ๐‘ฅ21 = min{โˆ’๐‘Ž21 + ๐‘11 , โˆ’๐‘Ž22 + ๐‘21, โ€ฆ , โˆ’๐‘Ž2๐‘˜ + ๐‘๐‘›1 } ๐‘ฅ22 = min{โˆ’๐‘Ž21 + ๐‘12 , โˆ’๐‘Ž22 + ๐‘22, โ€ฆ , โˆ’๐‘Ž2๐‘˜ + ๐‘๐‘›2 } โ‹ฎ ๐‘ฅ2๐‘™ = min{โˆ’๐‘Ž21 + ๐‘1๐‘› , โˆ’๐‘Ž22 + ๐‘2๐‘›, โ€ฆ , โˆ’๐‘Ž2๐‘˜ + ๐‘๐‘›๐‘› } โ‹ฎ ๐‘ฅ๐‘˜1 = min{โˆ’๐‘Ž๐‘–1 + ๐‘11 , โˆ’๐‘Ž๐‘–2 + ๐‘21, โ€ฆ , โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘๐‘›1 } ๐‘ฅ๐‘˜2 = min{โˆ’๐‘Ž๐‘–1 + ๐‘12 , โˆ’๐‘Ž๐‘–2 + ๐‘22, โ€ฆ , โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘๐‘›2 } โ‹ฎ ๐‘ฅ๐‘˜๐‘™ = min{โˆ’๐‘Ž๐‘–1 + ๐‘1๐‘› , โˆ’๐‘Ž๐‘–2 + ๐‘2๐‘›, โ€ฆ , โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘๐‘›๐‘› } So, it can be written as 9553 Edelweiss Applied Science and Technology ISSN: 2576-8484 Vol. 8, No. 6: 9544-9554, 2024 DOI: 10.55214/25768484.v8i6.4034 ยฉ 2024 by the authors; licensee Learning Gate ๐‘‹๐‘˜๐‘™ = [ min{โˆ’๐‘Ž1๐‘˜ + ๐‘๐‘›1 } min{โˆ’๐‘Ž1๐‘˜ + ๐‘๐‘›2 } min{โˆ’๐‘Ž2๐‘˜ + ๐‘๐‘›1 } min{โˆ’๐‘Ž2๐‘˜ + ๐‘๐‘›2 } โ‹ฏ min{โˆ’๐‘Ž1๐‘˜ + ๐‘๐‘›๐‘› } โ‹ฏ min{โˆ’๐‘Ž2๐‘˜ + ๐‘๐‘›๐‘› } โ‹ฎ โ‹ฎ min{โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘๐‘›1 } min{โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘๐‘›2 } โ‹ฑ โ‹ฎ โ‹ฏ min{โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘๐‘›๐‘› } ] Suppose ๐‘ = ๐ด๐‘–๐‘— โˆ’ ๐ด๐‘™๐‘—, we have ๐‘‹๐‘˜๐‘™ = ๐‘› ๐‘š๐‘–๐‘› ๐‘– = 1 ๐‘› ๐‘š๐‘–๐‘› ๐‘— = 1 (โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘Ž๐‘–๐‘— โˆ’ ๐‘Ž๐‘™๐‘—) From the form ๐‘ฅ๐‘˜๐‘™ , we obtain a form that can be expressed ๐‘š โŠ• ๐‘˜ = 1 [ ๐‘š โŠ• ๐‘™ = 1 (๐ด๐‘–๐‘˜ + ๐‘‹๐‘˜๐‘™ + ๐ด๐‘™๐‘—)] = ๐ด๐‘–๐‘— . by determining whether or not there is a solution to the equation ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด with ๐ด โˆˆ โ„๐‘š๐‘–๐‘› ๐‘›ร—๐‘š. The ๐‘–๐‘— โˆ’th element in ๐ด โŠ— ๐‘‹ โŠ— ๐ด is [๐ด โŠ— ๐‘‹ โŠ— ๐ด]๐‘–๐‘— = ๐‘š โจโ€ฒ ๐‘˜ = 1 ๐‘› โจโ€ฒ ๐‘™ = 1 (๐ด๐‘–๐‘˜ + ๐‘‹๐‘˜๐‘™ + ๐ด๐‘™๐‘—). So, we get the equation ๐‘š โจโ€ฒ ๐‘˜ = 1 [ ๐‘› โจโ€ฒ ๐‘™ = 1 (๐ด๐‘–๐‘˜ + ๐‘‹๐‘˜๐‘™ + ๐ด๐‘™๐‘—)] = ๐ด๐‘–๐‘— โ€ฆโ€ฆโ€ฆโ€ฆโ€ฆ(3) If for each ๐‘˜, ๐‘™ is formed ๐‘“๐‘–๐‘—(๐‘‹๐‘˜๐‘™) = ๐ด๐‘–๐‘˜ + ๐‘‹๐‘˜๐‘™ + ๐ด๐‘™๐‘— โ€ฆโ€ฆ..(4) then equation (3) becomes ๐‘› โจ ๐‘– = 1 ๐‘š โจ ๐‘– = 1 ๐‘“๐‘–๐‘—(๐‘‹๐‘˜๐‘™) = ๐ด๐‘–๐‘— โ€ฆโ€ฆโ€ฆ(5) It is obtained that ๐‘‹๐‘˜๐‘™ = ๐‘› ๐‘š๐‘–๐‘› ๐‘– = 1 ๐‘› ๐‘š๐‘–๐‘› ๐‘— = 1 (โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘Ž๐‘–๐‘— โˆ’ ๐‘Ž๐‘™๐‘—) corresponds if substituted into the equation ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด. 4. Conclusions In this conclusion, the property is obtained that permutation is required determining the inverse matrix over min-plus algebra. We obtain several theorems that show the characteristics of the inverse of matrices in min-plus algebra, especially generalized matrices. The characterization is obtained by considering the characteristics of the solutions linear equations system over min-plus algebra. The generalized inverse of the matrix ๐ด โˆˆ ๐‘…๐‘š๐‘–๐‘› ๐‘›ร—๐‘› can be obtained by determining the matrix ๐‘‹ with entry ๐‘‹๐‘˜๐‘™ = ๐‘› ๐‘š๐‘–๐‘› ๐‘– = 1 ๐‘› ๐‘š๐‘–๐‘› ๐‘— = 1 (โˆ’๐‘Ž๐‘–๐‘˜ + ๐‘Ž๐‘–๐‘— โˆ’ ๐‘Ž๐‘™๐‘—) which satisfies ๐ด โŠ— ๐‘‹ โŠ— ๐ด = ๐ด. Copyright: ยฉ 2024 by the authors. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/). References [1] S. R. Lisapaly and E. R. Persulessy, โ€œSemiring,โ€ BAREKENG J. Ilmu Mat. dan Terap., vol. 5, no. 2, pp. 45โ€“47, 2011, doi: 10.30598/barekengvol5iss2pp45-47. [2] G. 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