Abstract. Let D (U, V, W) be an oriented 3-partite graph with | U | = p, |V| = q and |W | = r. For any vertex x in D(U,V,W), let dx^+ and dui^- be the outdegree and indegree ofx respectively. Define aui (o...Abstract. Let D (U, V, W) be an oriented 3-partite graph with | U | = p, |V| = q and |W | = r. For any vertex x in D(U,V,W), let dx^+ and dui^- be the outdegree and indegree ofx respectively. Define aui (or simply ai) = q + r + dui^+ - dui^-, bvj (or simply b j) = p + r + d^+vj - d^-vj and cwk (or simply ck) =p + q + dwk^+ -dwk^- as the scores of ui in U,vj in V and wk in W respectively. The set A of distinct scores of the vertices of D(U, V, W) is called its score set. In this paper, we prove that if a1 is a non-negative integer, ai(2 ≤ i ≤ n - 1) are even positive integers and an is any positive integer, then for n 〉 3, there exists an oriented 3-partite graph with the score set A ={a1,Σ2i=1 ai,…,Σni=1 ai}, except when A = {0, 2, 3}. Some more results for score sets in oriented 3-partite graphs are obtained.展开更多
Several possible definitions of local injectivity for a homomorphism of an oriented graph G to an oriented graph H are considered. In each case, we determine the complexity of deciding whether there exists such a homo...Several possible definitions of local injectivity for a homomorphism of an oriented graph G to an oriented graph H are considered. In each case, we determine the complexity of deciding whether there exists such a homomorphism when G is given and H is a fixed tournament on three or fewer vertices. Each possible definition leads to a locally-injective oriented colouring problem. A dichotomy theorem is proved in each case.展开更多
Let D be a diagraph of order n≥9 and δ≥n-2. If for every pairof vertices u, v∈V(D) , either uv∈ A(D) or . Theauthor has proved D is pancyclic before. In this paper we suppose n≥6 in-stead of n≥9 in above condit...Let D be a diagraph of order n≥9 and δ≥n-2. If for every pairof vertices u, v∈V(D) , either uv∈ A(D) or . Theauthor has proved D is pancyclic before. In this paper we suppose n≥6 in-stead of n≥9 in above condition, and show the same result holds except 6s展开更多
This paper proposes an extended system dependence graph called AspectSDG to represent control and data dependences for AspeetC++ programs, and presents an approach for the construction of AspectSDG. This approach de...This paper proposes an extended system dependence graph called AspectSDG to represent control and data dependences for AspeetC++ programs, and presents an approach for the construction of AspectSDG. This approach decomposes aspect-oriented programs into three parts: component codes, aspect codes, and weaving codes. It constructs program dependence graphs (PDGs) for each part, and then connects the PDGs at call sites to form the complete AspectSDG. The AspectSDG can deal with advice precedence correctly, and represent the additional dependences caused by aspect codes. Based on this model, we introduce how to compute a static slice of an AspectC+ + program.展开更多
An oriented tripartite graph is the result of assigning a direction to each edge of a simple tripartite graph. For any vertex x in an oriented tripartite graph D(U, V, W), let dx^+ and dx^- denote the outdegree and...An oriented tripartite graph is the result of assigning a direction to each edge of a simple tripartite graph. For any vertex x in an oriented tripartite graph D(U, V, W), let dx^+ and dx^- denote the outdegree and indegree respectively of x. Define aui: dui^+ - dus^-, bvj = dvj^+ - dvj^- and cwk = dwk^+ - dwk^- as the imbalances of the vertices ui in U, vj in V and wk in W respectively. In this paper, we obtain criteria for sequences of integers to be the imbalances of some oriented tripartite graph. Keywords Digraph, imbalance, outdegree, indegree, oriented graph, oriented tripartite graph, arc展开更多
Program slice has many applications such as program debugging, testing, maintenance, and complexity measurement. A static slice consists of all statements in program P that may effect the value of variable v a...Program slice has many applications such as program debugging, testing, maintenance, and complexity measurement. A static slice consists of all statements in program P that may effect the value of variable v at some point p , and a dynamic slice consists only of statements that influence the value of variable occurrence for specific program inputs. In this paper, we concern the problem of dynamic slicing of object oriented programs which, to our knowledge, has not been addressed in the literatures. To solve this problem, we present the dynamic object oriented dependence graph (DODG)which is an arc classified digraph to explicitly represent various dynamic dependence between statement instances for a particular execution of an object oriented program. Based on the DODG, we present a two phase backward algorithm for computing a dynamic slice of an object oriented program.展开更多
We say that a parameter p of directed graphs has the interval property if for every graph G?and orientations of G, p can take every value between its minimum and maximum values. Let λbe the length of the lo...We say that a parameter p of directed graphs has the interval property if for every graph G?and orientations of G, p can take every value between its minimum and maximum values. Let λbe the length of the longest directed path. A question asked by C. Lin in [1] is equivalent to the question of whether λhas the interval property. In this note, we answer this question in the affirmative. We also show that the diameter of directed graphs does not have the interval property.展开更多
If is a permutation of , the graph has vertices where xy is an edge of if and only if (x, y) or (y, x) is an inversion of . Any graph isomorphic to is called a permutation graph. In 1967 Gallai characterized permutati...If is a permutation of , the graph has vertices where xy is an edge of if and only if (x, y) or (y, x) is an inversion of . Any graph isomorphic to is called a permutation graph. In 1967 Gallai characterized permutation graphs in terms of forbidden induced subgraphs. In 1971 Pnueli, Lempel, and Even showed that a graph is a permutation graph if and only if both the graph and its complement have transitive orientations. In 2010 Limouzy characterized permutation graphs in terms of forbidden Seidel minors. In this paper, we characterize permutation graphs in terms of a cohesive order of its vertices. We show that only the caterpillars are permutation graphs among the trees. A simple method of constructing permutation graphs is also presented here.展开更多
This paper continues the research on theoretical foundations for computer simulation.We introduce the concept of word-updating dynamical systems(WDS)on directed graphs,which is a kind of generalization of sequential d...This paper continues the research on theoretical foundations for computer simulation.We introduce the concept of word-updating dynamical systems(WDS)on directed graphs,which is a kind of generalization of sequential dynamical systems(SDS)on graphs.Some properties on WDS,especially some results on NOR-WDS,which are different from that on NOR-SDS,are obtained.展开更多
In this paper, the oriented matrix analysis (OMA) method of system reliability has been discussed. OMA uses a oriented fault graph instead of a traditional fault tree model. By defining the specific logic operation an...In this paper, the oriented matrix analysis (OMA) method of system reliability has been discussed. OMA uses a oriented fault graph instead of a traditional fault tree model. By defining the specific logic operation and calculating a reachability matrix, the cut sets can be formed directly and the minimum cut sets can be easily obtained.展开更多
Satellite networks have many inherent advantages over terrestrial networks and have become an important part of the global network infrastructure.Routing aimed at satellite networks has become a hot and challenging re...Satellite networks have many inherent advantages over terrestrial networks and have become an important part of the global network infrastructure.Routing aimed at satellite networks has become a hot and challenging research topic.Satellite networks,which are special kind of Delay Tolerant Networks(DTN),can also adopt the routing solutions of DTN.Among the many routing proposals,Contact Graph Routing(CGR) is an excellent candidate,since it is designed particularly for use in highly deterministic space networks.The applicability of CGR in satellite networks is evaluated by utilizing the space oriented DTN gateway model based on OPNET(Optimized Network Engineering Tool).Link failures are solved with neighbor discovery mechanism and route recomputation.Earth observation scenario is used in the simulations to investigate CGR's performance.The results show that the CGR performances are better in terms of effectively utilizing satellite networks resources to calculate continuous route path and alternative route can be successfully calculated under link failures by utilizing fault tolerance scheme.展开更多
Nowadays, one of the IT challenges faced by many enterprises is the maintenance of their legacy system and migration of those systems to modern and flexible platform. In this paper, we study the network properties of ...Nowadays, one of the IT challenges faced by many enterprises is the maintenance of their legacy system and migration of those systems to modern and flexible platform. In this paper, we study the network properties of software call graphs, and utilize the network theories to understand the business logic of legacy system. The call graphs turn out approximately scale-free and small world network properties. This finding provides new insight to understand the business logic of legacy system: the methods in a program can be naturedly partitioned into the business methods group and supportive methods group. Moreover, the result is also very helpful in reusing valuable functionality and identifying what services should be to expose in the migration from legacy to modern SOA context.展开更多
文摘Abstract. Let D (U, V, W) be an oriented 3-partite graph with | U | = p, |V| = q and |W | = r. For any vertex x in D(U,V,W), let dx^+ and dui^- be the outdegree and indegree ofx respectively. Define aui (or simply ai) = q + r + dui^+ - dui^-, bvj (or simply b j) = p + r + d^+vj - d^-vj and cwk (or simply ck) =p + q + dwk^+ -dwk^- as the scores of ui in U,vj in V and wk in W respectively. The set A of distinct scores of the vertices of D(U, V, W) is called its score set. In this paper, we prove that if a1 is a non-negative integer, ai(2 ≤ i ≤ n - 1) are even positive integers and an is any positive integer, then for n 〉 3, there exists an oriented 3-partite graph with the score set A ={a1,Σ2i=1 ai,…,Σni=1 ai}, except when A = {0, 2, 3}. Some more results for score sets in oriented 3-partite graphs are obtained.
文摘Several possible definitions of local injectivity for a homomorphism of an oriented graph G to an oriented graph H are considered. In each case, we determine the complexity of deciding whether there exists such a homomorphism when G is given and H is a fixed tournament on three or fewer vertices. Each possible definition leads to a locally-injective oriented colouring problem. A dichotomy theorem is proved in each case.
文摘Let D be a diagraph of order n≥9 and δ≥n-2. If for every pairof vertices u, v∈V(D) , either uv∈ A(D) or . Theauthor has proved D is pancyclic before. In this paper we suppose n≥6 in-stead of n≥9 in above condition, and show the same result holds except 6s
基金Supported by the National Science Foundation forDistinguished Young Scholars (60425206) the National Natural Sci-ence Foundation of China ( 90412003 , 60373066 , 60403016 ,60503033) the National Basic Research Programof China (973 Pro-gram2002CB312000)
文摘This paper proposes an extended system dependence graph called AspectSDG to represent control and data dependences for AspeetC++ programs, and presents an approach for the construction of AspectSDG. This approach decomposes aspect-oriented programs into three parts: component codes, aspect codes, and weaving codes. It constructs program dependence graphs (PDGs) for each part, and then connects the PDGs at call sites to form the complete AspectSDG. The AspectSDG can deal with advice precedence correctly, and represent the additional dependences caused by aspect codes. Based on this model, we introduce how to compute a static slice of an AspectC+ + program.
文摘An oriented tripartite graph is the result of assigning a direction to each edge of a simple tripartite graph. For any vertex x in an oriented tripartite graph D(U, V, W), let dx^+ and dx^- denote the outdegree and indegree respectively of x. Define aui: dui^+ - dus^-, bvj = dvj^+ - dvj^- and cwk = dwk^+ - dwk^- as the imbalances of the vertices ui in U, vj in V and wk in W respectively. In this paper, we obtain criteria for sequences of integers to be the imbalances of some oriented tripartite graph. Keywords Digraph, imbalance, outdegree, indegree, oriented graph, oriented tripartite graph, arc
文摘Program slice has many applications such as program debugging, testing, maintenance, and complexity measurement. A static slice consists of all statements in program P that may effect the value of variable v at some point p , and a dynamic slice consists only of statements that influence the value of variable occurrence for specific program inputs. In this paper, we concern the problem of dynamic slicing of object oriented programs which, to our knowledge, has not been addressed in the literatures. To solve this problem, we present the dynamic object oriented dependence graph (DODG)which is an arc classified digraph to explicitly represent various dynamic dependence between statement instances for a particular execution of an object oriented program. Based on the DODG, we present a two phase backward algorithm for computing a dynamic slice of an object oriented program.
文摘We say that a parameter p of directed graphs has the interval property if for every graph G?and orientations of G, p can take every value between its minimum and maximum values. Let λbe the length of the longest directed path. A question asked by C. Lin in [1] is equivalent to the question of whether λhas the interval property. In this note, we answer this question in the affirmative. We also show that the diameter of directed graphs does not have the interval property.
文摘If is a permutation of , the graph has vertices where xy is an edge of if and only if (x, y) or (y, x) is an inversion of . Any graph isomorphic to is called a permutation graph. In 1967 Gallai characterized permutation graphs in terms of forbidden induced subgraphs. In 1971 Pnueli, Lempel, and Even showed that a graph is a permutation graph if and only if both the graph and its complement have transitive orientations. In 2010 Limouzy characterized permutation graphs in terms of forbidden Seidel minors. In this paper, we characterize permutation graphs in terms of a cohesive order of its vertices. We show that only the caterpillars are permutation graphs among the trees. A simple method of constructing permutation graphs is also presented here.
文摘This paper continues the research on theoretical foundations for computer simulation.We introduce the concept of word-updating dynamical systems(WDS)on directed graphs,which is a kind of generalization of sequential dynamical systems(SDS)on graphs.Some properties on WDS,especially some results on NOR-WDS,which are different from that on NOR-SDS,are obtained.
文摘In this paper, the oriented matrix analysis (OMA) method of system reliability has been discussed. OMA uses a oriented fault graph instead of a traditional fault tree model. By defining the specific logic operation and calculating a reachability matrix, the cut sets can be formed directly and the minimum cut sets can be easily obtained.
基金Supported by the open project of Communication network transmission and distribution technologies Key Laboratory(ITD-12005/K1260011)the National Natural Science Foundation of China(61371126) and the National Natural Science Foundation of China(60903195)
文摘Satellite networks have many inherent advantages over terrestrial networks and have become an important part of the global network infrastructure.Routing aimed at satellite networks has become a hot and challenging research topic.Satellite networks,which are special kind of Delay Tolerant Networks(DTN),can also adopt the routing solutions of DTN.Among the many routing proposals,Contact Graph Routing(CGR) is an excellent candidate,since it is designed particularly for use in highly deterministic space networks.The applicability of CGR in satellite networks is evaluated by utilizing the space oriented DTN gateway model based on OPNET(Optimized Network Engineering Tool).Link failures are solved with neighbor discovery mechanism and route recomputation.Earth observation scenario is used in the simulations to investigate CGR's performance.The results show that the CGR performances are better in terms of effectively utilizing satellite networks resources to calculate continuous route path and alternative route can be successfully calculated under link failures by utilizing fault tolerance scheme.
文摘Nowadays, one of the IT challenges faced by many enterprises is the maintenance of their legacy system and migration of those systems to modern and flexible platform. In this paper, we study the network properties of software call graphs, and utilize the network theories to understand the business logic of legacy system. The call graphs turn out approximately scale-free and small world network properties. This finding provides new insight to understand the business logic of legacy system: the methods in a program can be naturedly partitioned into the business methods group and supportive methods group. Moreover, the result is also very helpful in reusing valuable functionality and identifying what services should be to expose in the migration from legacy to modern SOA context.