To date, it is unknown whether it is possible to construct a complete graph invariant in polynomial time, so fast algorithms for checking non-isomorphism are important, including heuristic algorithms, and for successf...To date, it is unknown whether it is possible to construct a complete graph invariant in polynomial time, so fast algorithms for checking non-isomorphism are important, including heuristic algorithms, and for successful implementations of such heuristics, both the tasks of some modification of previously described graph invariants and the description of new invariants remain relevant. Many of the described invariants make it possible to distinguish a larger number of graphs in the real time of a computer program. In this paper, we propose an invariant for a special kind of directed graphs, namely, for tournaments. The last ones, from our point of view, are interesting because when fixing the order of vertices, the number of different tournaments is exactly equal to the number of undirected graphs, also with fixing the order of vertices. In the invariant we are considering, all possible tournaments consisting of a subset of vertices of a given digraph with the same set of arcs are iterated over. For such subset tournaments, the places are calculated in the usual way, which are summed up to obtain the final values of the points of the vertices;these points form the proposed invariant. As we expected, calculations of the new invariant showed that it does not coincide with the most natural invariant for tournaments, in which the number of points is calculated for each participant. So far, we have conducted a small number of computational experiments, and the minimum value of the pair correlation between the sequences representing these two invariants that we found is for dimension 15.展开更多
With the rapid development of the Internet,people pay more and more attention to the protection of privacy.The second-generation onion routing system Tor is the most commonly used among anonymous communication systems...With the rapid development of the Internet,people pay more and more attention to the protection of privacy.The second-generation onion routing system Tor is the most commonly used among anonymous communication systems,which can be used to protect user privacy effectively.In recent years,Tor’s congestion problem has become the focus of attention,and it can affect Tor’s performance even user experience.Firstly,we investigate the causes of Tor network congestion and summarize some link scheduling algorithms proposed in recent years.Then we propose the link scheduling algorithm SWRR based on WRR(Weighted Round Robin).In this process,we design multiple weight functions and compare the performance of these weight functions under different congestion conditions,and the appropriate weight function is selected to be used in our algorithms based on the experiment results.Finally,we also compare the performance of SWRR with other link scheduling algorithms under different congestion conditions by experiments,and verify the effectiveness of the algorithm SWRR.展开更多
Let Γm，n^* denote all m × n strongly connected bipartite tournaments and a(m, n) the maximal integer k such that every m × n bipartite tournament contains at least a k × k transitive bipartite subtour...Let Γm，n^* denote all m × n strongly connected bipartite tournaments and a(m, n) the maximal integer k such that every m × n bipartite tournament contains at least a k × k transitive bipartite subtournament. Let t ( m, n, k, l ) = max{t( Tm,n，k, l ) : Tm,n∈Γm，n^*}, where t ( Tm,n, k, l ) is the number of k × l(k≥2,l≥2) transitive bipartite subtournaments contained in Tm,n∈Γm，n^*. We obtain a method of graph theory for solving some integral programmings, investigate the upper bounds of a(m,n) and obtain t (m,n, k，l).展开更多
Round-robin differential phase shift （RRDPS） is a novel quantum key distribution protocol which can bound information leakage without monitoring signal disturbance. In this work, to decrease the effect of the vacuum...Round-robin differential phase shift （RRDPS） is a novel quantum key distribution protocol which can bound information leakage without monitoring signal disturbance. In this work, to decrease the effect of the vacuum component in a weak coherent pulses source, we employ a practical decoy-state scheme with heralded singlephoton source for the RRDPS protocol and analyze the performance of this method. In this scheme, only two decoy states are needed and the yields of single-photon state and multi-photon states, as well as the bit error rates of each photon states, can be estimated. The final key rate of this scheme is bounded and simulated over transmission distance. The results show that the two-decoy-state method with heralded single-photon source performs better than the two-decoy-state method with weak coherent pulses.展开更多
Let T=(V,A)be a tournament of order n and T_i,…,T_m be diconnectedcomponents in T.If uv ∈A and P is a directed path of length k-1(k≥3)from u to v,We call P ∪{uv}a 1-antidirected cycle of length k.Let k be an integ...Let T=(V,A)be a tournament of order n and T_i,…,T_m be diconnectedcomponents in T.If uv ∈A and P is a directed path of length k-1(k≥3)from u to v,We call P ∪{uv}a 1-antidirected cycle of length k.Let k be an integer satisfying 3≤k≤n.If every arc e∈A is contained in a 1-antidirected cycle of length k,we will refer toT as arc k 1-antidirected cyclic.If T is arc k 1-antidirected cyclic for k=3,4,…,n,T iscalled arc 1-antidirected pancyclic.In this paper,we prove that T is arc 1-antidirectedpancyclic if and only if T satisfies one of the following conditions:(i)2≤m≤3 and forany T_i,every arc e∈T_i is contained in a Hamilton path in T_i;(ii)m=1,except some spe-cial tournaments which are to be shown.展开更多
In this paper, we present a new sufficient condition on degrees for a bipartite tournament to be Hamiltonian, that is, if an n × n bipartite tournament T satisfies the condition W（n - 3）, then T is Hamiltonian,...In this paper, we present a new sufficient condition on degrees for a bipartite tournament to be Hamiltonian, that is, if an n × n bipartite tournament T satisfies the condition W（n - 3）, then T is Hamiltonian, except for four exceptional graphs. This result is shown to be best possible in a sense.展开更多
Scheduling sports leagues has drawn significant attention to itself in recent years, as it involves considerable revenue as well as challenging combinatorial optimization problems. A particular class of these problems...Scheduling sports leagues has drawn significant attention to itself in recent years, as it involves considerable revenue as well as challenging combinatorial optimization problems. A particular class of these problems is the Traveling Tournament Problem (TTP) which focuses on minimizing the total traveling distance for teams. In this paper, an efficient simulated annealing approach is presented for TTP which applies two simultaneous and disparate models for the problem in order to search the solutions space more effectively. Also, a computationally efficient modified greedy scheme is proposed for constructing a favorable initial solution for the simulated annealing algorithm. Our computational experiments, carried out on standard instances, demonstrate that this approach competes with previous offered methods in quality of found solutions and their computational time.展开更多
The exploitation and utilization of the tour resources of tournament athletics, including skiling, boat sailing, archery, ice engraving, snow engrav ing, has become a new trend of the development of Chinese tourism. D...The exploitation and utilization of the tour resources of tournament athletics, including skiling, boat sailing, archery, ice engraving, snow engrav ing, has become a new trend of the development of Chinese tourism. Due to the un ique cold climate and superior geographic location,Harbin is a promising city f or developing tour resources of tournament athletics. Based on the analysis of t he superiority and peculiarity of Harbin,the speculation on development of tour resources of tournament athletics in Harbin is proposed as follows:1) Harbin s hould develop its special tour resources of tournament athletics associated with needs of market; 2) Harbin should take the advantages of rich resources and dev elop ice and snow entertainment in winter and travel for sight-seeing and spend ing summer; 3) the adjustment of the layout of ice and snow resources should be based on the idea of taking Harbin as the center and all-side opening at the la rge scale in the way of radiation; 4) tourism should be developed by the combine d efforts of various departments to make feasible plan, and the organizers shoul d pay much attention to ensuring the safety of tourists.展开更多
A framework is provided for analyzing the time and resource requirements for a tournament where matches are played to a best-of-N format, to ensure maximal use of available facilities and a maximal number of competito...A framework is provided for analyzing the time and resource requirements for a tournament where matches are played to a best-of-N format, to ensure maximal use of available facilities and a maximal number of competitors. A baseline of average length of games and number of games played per match is necessary. The analysis informing development of the framework was carried out in the context of the sport of golf croquet. Based on the results of this analysis, golf croquet tournaments should have four best-of-three matches scheduled per court per day to optimize playing time and minimize the need to play matches outside regular playing hours.展开更多
The Sports Garbage Pickup Tournament is a sports event that incorporates elements of competition into cleaning activities,as opposed to traditional cleaning activities.As of the end of December 2016,a total of 552 Spo...The Sports Garbage Pickup Tournament is a sports event that incorporates elements of competition into cleaning activities,as opposed to traditional cleaning activities.As of the end of December 2016,a total of 552 Sports Garbage Pickup Tournaments have been held,mobilizing a cumulative total number of 62,989 people.As each tournament brings a revenue of over 300,000 yen,the total sales so far would be more than 165,000,000 yen.This game was recently reported on the International Olympic Committee channel.The garbage issue,a social problem for local communities,should be solved by residents,visitors,and workers themselves through sports,cooperating with local governments.This is an eco-friendly sport aimed at“solving local social problems through sports.”Sports Garbage Pickup Tournaments can be held anywhere,inside the city or in a natural environment.In addition,the competition allows participants to visually understand the environmental capacity of garbage produced in the community,as the points are weighted according to the types of garbage.The Sports Garbage Pickup Tournament is an educational program for sustainable development with emphasis on experience,pursuit,and practice,and also an action-based program aimed at promoting spontaneous action.This is an optimal competition for participants to acquire skills through mutual communication.As children,adults,and people with disabilities can play together,the competition will promote communication across the generations.展开更多
Recently,a round-robin differential phase-shift（RRDPS） protocol was proposed[Nature 509,475（2014）],in which the amount of leakage is bounded without monitoring the signal disturbance.Introducing states of the phas...Recently,a round-robin differential phase-shift（RRDPS） protocol was proposed[Nature 509,475（2014）],in which the amount of leakage is bounded without monitoring the signal disturbance.Introducing states of the phase-encoded Bennett-Brassard 1984 protocol（PE-BB84） to the RRDPS,this paper presents another quantum key distribution protocol called round-robin differential quadrature phase-shift（RRDQPS） quantum key distribution.Regarding a train of many pulses as a single packet,the sender modulates the phase of each pulse by one of {0,π/2,π,3π/2},then the receiver measures each packet with a Mach-Zehnder interferometer having a phase basis of 0 or π/2.The RRDQPS protocol can be implemented with essential similar hardware to the PE-BB84,so it has great compatibility with the current quantum system.Here we analyze the security of the RRDQPS protocol against the intercept-resend attack and the beam-splitting attack.Results show that the proposed protocol inherits the advantages arising from the simplicity of the RRDPS protocol and is more robust against these attacks than the original protocol.展开更多
文摘To date, it is unknown whether it is possible to construct a complete graph invariant in polynomial time, so fast algorithms for checking non-isomorphism are important, including heuristic algorithms, and for successful implementations of such heuristics, both the tasks of some modification of previously described graph invariants and the description of new invariants remain relevant. Many of the described invariants make it possible to distinguish a larger number of graphs in the real time of a computer program. In this paper, we propose an invariant for a special kind of directed graphs, namely, for tournaments. The last ones, from our point of view, are interesting because when fixing the order of vertices, the number of different tournaments is exactly equal to the number of undirected graphs, also with fixing the order of vertices. In the invariant we are considering, all possible tournaments consisting of a subset of vertices of a given digraph with the same set of arcs are iterated over. For such subset tournaments, the places are calculated in the usual way, which are summed up to obtain the final values of the points of the vertices;these points form the proposed invariant. As we expected, calculations of the new invariant showed that it does not coincide with the most natural invariant for tournaments, in which the number of points is calculated for each participant. So far, we have conducted a small number of computational experiments, and the minimum value of the pair correlation between the sequences representing these two invariants that we found is for dimension 15.
基金This work is supported by the National Natural Science Foundation of China(Grant No.61170273,No.U1536111)and the China Scholarship Council(No.[2013]3050).In addition,we express our sincere gratitude to Lingling Gong,Meng Luo,Zhimin Lin,Peiyuan Li and the anonymous reviewers for their valuable comments and suggestions.
文摘With the rapid development of the Internet,people pay more and more attention to the protection of privacy.The second-generation onion routing system Tor is the most commonly used among anonymous communication systems,which can be used to protect user privacy effectively.In recent years,Tor’s congestion problem has become the focus of attention,and it can affect Tor’s performance even user experience.Firstly,we investigate the causes of Tor network congestion and summarize some link scheduling algorithms proposed in recent years.Then we propose the link scheduling algorithm SWRR based on WRR(Weighted Round Robin).In this process,we design multiple weight functions and compare the performance of these weight functions under different congestion conditions,and the appropriate weight function is selected to be used in our algorithms based on the experiment results.Finally,we also compare the performance of SWRR with other link scheduling algorithms under different congestion conditions by experiments,and verify the effectiveness of the algorithm SWRR.
文摘Let Γm，n^* denote all m × n strongly connected bipartite tournaments and a(m, n) the maximal integer k such that every m × n bipartite tournament contains at least a k × k transitive bipartite subtournament. Let t ( m, n, k, l ) = max{t( Tm,n，k, l ) : Tm,n∈Γm，n^*}, where t ( Tm,n, k, l ) is the number of k × l(k≥2,l≥2) transitive bipartite subtournaments contained in Tm,n∈Γm，n^*. We obtain a method of graph theory for solving some integral programmings, investigate the upper bounds of a(m,n) and obtain t (m,n, k，l).
基金Supported by the National Basic Research Program of China under Grant No 2013CB338002the National Natural Science Foundation of China under Grant Nos 11304397 and 61505261
文摘Round-robin differential phase shift （RRDPS） is a novel quantum key distribution protocol which can bound information leakage without monitoring signal disturbance. In this work, to decrease the effect of the vacuum component in a weak coherent pulses source, we employ a practical decoy-state scheme with heralded singlephoton source for the RRDPS protocol and analyze the performance of this method. In this scheme, only two decoy states are needed and the yields of single-photon state and multi-photon states, as well as the bit error rates of each photon states, can be estimated. The final key rate of this scheme is bounded and simulated over transmission distance. The results show that the two-decoy-state method with heralded single-photon source performs better than the two-decoy-state method with weak coherent pulses.
文摘Let T=(V,A)be a tournament of order n and T_i,…,T_m be diconnectedcomponents in T.If uv ∈A and P is a directed path of length k-1(k≥3)from u to v,We call P ∪{uv}a 1-antidirected cycle of length k.Let k be an integer satisfying 3≤k≤n.If every arc e∈A is contained in a 1-antidirected cycle of length k,we will refer toT as arc k 1-antidirected cyclic.If T is arc k 1-antidirected cyclic for k=3,4,…,n,T iscalled arc 1-antidirected pancyclic.In this paper,we prove that T is arc 1-antidirectedpancyclic if and only if T satisfies one of the following conditions:(i)2≤m≤3 and forany T_i,every arc e∈T_i is contained in a Hamilton path in T_i;(ii)m=1,except some spe-cial tournaments which are to be shown.
文摘In this paper, we present a new sufficient condition on degrees for a bipartite tournament to be Hamiltonian, that is, if an n × n bipartite tournament T satisfies the condition W（n - 3）, then T is Hamiltonian, except for four exceptional graphs. This result is shown to be best possible in a sense.
文摘Scheduling sports leagues has drawn significant attention to itself in recent years, as it involves considerable revenue as well as challenging combinatorial optimization problems. A particular class of these problems is the Traveling Tournament Problem (TTP) which focuses on minimizing the total traveling distance for teams. In this paper, an efficient simulated annealing approach is presented for TTP which applies two simultaneous and disparate models for the problem in order to search the solutions space more effectively. Also, a computationally efficient modified greedy scheme is proposed for constructing a favorable initial solution for the simulated annealing algorithm. Our computational experiments, carried out on standard instances, demonstrate that this approach competes with previous offered methods in quality of found solutions and their computational time.
文摘The exploitation and utilization of the tour resources of tournament athletics, including skiling, boat sailing, archery, ice engraving, snow engrav ing, has become a new trend of the development of Chinese tourism. Due to the un ique cold climate and superior geographic location,Harbin is a promising city f or developing tour resources of tournament athletics. Based on the analysis of t he superiority and peculiarity of Harbin,the speculation on development of tour resources of tournament athletics in Harbin is proposed as follows:1) Harbin s hould develop its special tour resources of tournament athletics associated with needs of market; 2) Harbin should take the advantages of rich resources and dev elop ice and snow entertainment in winter and travel for sight-seeing and spend ing summer; 3) the adjustment of the layout of ice and snow resources should be based on the idea of taking Harbin as the center and all-side opening at the la rge scale in the way of radiation; 4) tourism should be developed by the combine d efforts of various departments to make feasible plan, and the organizers shoul d pay much attention to ensuring the safety of tourists.
文摘A framework is provided for analyzing the time and resource requirements for a tournament where matches are played to a best-of-N format, to ensure maximal use of available facilities and a maximal number of competitors. A baseline of average length of games and number of games played per match is necessary. The analysis informing development of the framework was carried out in the context of the sport of golf croquet. Based on the results of this analysis, golf croquet tournaments should have four best-of-three matches scheduled per court per day to optimize playing time and minimize the need to play matches outside regular playing hours.
文摘The Sports Garbage Pickup Tournament is a sports event that incorporates elements of competition into cleaning activities,as opposed to traditional cleaning activities.As of the end of December 2016,a total of 552 Sports Garbage Pickup Tournaments have been held,mobilizing a cumulative total number of 62,989 people.As each tournament brings a revenue of over 300,000 yen,the total sales so far would be more than 165,000,000 yen.This game was recently reported on the International Olympic Committee channel.The garbage issue,a social problem for local communities,should be solved by residents,visitors,and workers themselves through sports,cooperating with local governments.This is an eco-friendly sport aimed at“solving local social problems through sports.”Sports Garbage Pickup Tournaments can be held anywhere,inside the city or in a natural environment.In addition,the competition allows participants to visually understand the environmental capacity of garbage produced in the community,as the points are weighted according to the types of garbage.The Sports Garbage Pickup Tournament is an educational program for sustainable development with emphasis on experience,pursuit,and practice,and also an action-based program aimed at promoting spontaneous action.This is an optimal competition for participants to acquire skills through mutual communication.As children,adults,and people with disabilities can play together,the competition will promote communication across the generations.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61505261 and 11304397)the National Basic Research Program of China(Grant No.2013CB338002)
文摘Recently,a round-robin differential phase-shift（RRDPS） protocol was proposed[Nature 509,475（2014）],in which the amount of leakage is bounded without monitoring the signal disturbance.Introducing states of the phase-encoded Bennett-Brassard 1984 protocol（PE-BB84） to the RRDPS,this paper presents another quantum key distribution protocol called round-robin differential quadrature phase-shift（RRDQPS） quantum key distribution.Regarding a train of many pulses as a single packet,the sender modulates the phase of each pulse by one of {0,π/2,π,3π/2},then the receiver measures each packet with a Mach-Zehnder interferometer having a phase basis of 0 or π/2.The RRDQPS protocol can be implemented with essential similar hardware to the PE-BB84,so it has great compatibility with the current quantum system.Here we analyze the security of the RRDQPS protocol against the intercept-resend attack and the beam-splitting attack.Results show that the proposed protocol inherits the advantages arising from the simplicity of the RRDPS protocol and is more robust against these attacks than the original protocol.
