Given two graphs G and H,the Ramsey number R(G,H) is the minimum integer N such that any two-coloring of the edges of K_(N) in red or blue yields a red G or a blue H.Let v(G) be the number of vertices of G and χ(G) b...Given two graphs G and H,the Ramsey number R(G,H) is the minimum integer N such that any two-coloring of the edges of K_(N) in red or blue yields a red G or a blue H.Let v(G) be the number of vertices of G and χ(G) be the chromatic number of G.Let s(G) denote the chromatic surplus of G,the number of vertices in a minimum color class among all proper χ(G)-colorings of G.Burr showed that R(G,H)≥(v(G)-1)(χ(H)-1)+s(H) if G is connected and v(G)≥s(H).A connected graph G is H-good if R(G,H)=(v(G)-1)(χ(H)-1)+s(H).Let tH denote the disjoint union of t copies of graph H,and let G∨H denote the join of G and H.Denote a complete graph on n vertices by K_(n),and a tree on n vertices by T_(n).Denote a book with n pages by B_(n),i.e.,the join K_(2) ∨■.Erd?s,Faudree,Rousseau and Schelp proved that T_(n) is B_(m)-good if n≥3m-3.In this paper,we obtain the exact Ramsey number of T_(n) versus 2B_(2).Our result implies that T_(n) is 2B_(2)-good if n≥5.展开更多
For an integer r≥2 and bipartite graphs Hi,where 1≤i≤r,the bipartite Ramsey number br(H1,H2,…,Hr)is the minimum integer N such that any r-edge coloring of the complete bipartite graph KN;N contains a monochromatic...For an integer r≥2 and bipartite graphs Hi,where 1≤i≤r,the bipartite Ramsey number br(H1,H2,…,Hr)is the minimum integer N such that any r-edge coloring of the complete bipartite graph KN;N contains a monochromatic subgraph isomorphic to Hi in color i for some 1≤i≤r.We show that if r≥3;α1,α2>0,αj+2≥[(j+2)!-1]Σi=1^(j+1)α1 for j=1,2…r-2,then br(C2[α1n],C2[α2n],…,C2[αrn]=(Σ=j=1^(r)a j+o(1))n.展开更多
We present a detailed analysis of phase sensitivity for a nonlinear Ramsey interferometer, which utilize effective mean-field interaction of a two-component Bose-Einstein condensate in phase ac- cumulation. For large ...We present a detailed analysis of phase sensitivity for a nonlinear Ramsey interferometer, which utilize effective mean-field interaction of a two-component Bose-Einstein condensate in phase ac- cumulation. For large enough particle number N and small phase shift φ, analytical results of the Ramsey signal and the phase sensitivity are derived for a product coherent state θ, 0）. When collisional dephasing is absent, we confirm that the optimal sensitivity scales as 2/N3/2 for polar angle of the initial state θ = π/4 or 3π/4. The best-sensitivity phase satisfies different transcendental equations, depending upon the initial state and the observable being measured after the phase accumulation. In the presence of the collisional dephasing, we show that the N-3/2-scaling rule of the sensitivity maintains with spin operators jx and jy measurements. A slightly better sensitivity is attainable for optimal coherent state with θ = π/6 or 5π/6.展开更多
Herein,we propose a novel strategy for implementing a direct readout of the symmetric characteristic function of the quantum states of quantum fields without the involvement of idealized measurements,an aspect that ha...Herein,we propose a novel strategy for implementing a direct readout of the symmetric characteristic function of the quantum states of quantum fields without the involvement of idealized measurements,an aspect that has always been deemed ill-defined in quantum field theory.This proposed scheme relies on the quantum control and measurements of an auxiliary qubit locally coupled to the quantum fields.By mapping the expectation values of both the real and imaginary parts of the field displacement operator to the qubit states,the qubit's readout provides complete information regarding the symmetric characteristic function.We characterize our technique by applying it to the Kubo-Martin-Schwinger(thermal)and squeezed states of a quantum scalar field.In addition,we have discussed general applications of this approach to analogue-gravity systems,such as Bose-Einstein condensates,within the scope of state-of-the-art experimental capabilities.This proposed strategy may serve as an essential in understanding and optimizing the control of quantum fields for relativistic quantum information applications,particularly in exploring the interplay between gravity and quantum,for example,the relation to locality,causality,and information.展开更多
The Ramsey number is a foundational result in combinatorics. This article will introduce Ramsey number with the method of graph theory, and the Ramsey pricing theory is applied to the sales price and study of cross su...The Ramsey number is a foundational result in combinatorics. This article will introduce Ramsey number with the method of graph theory, and the Ramsey pricing theory is applied to the sales price and study of cross subsidy. Based on the status of our sales price and cross subsidy, Ramsey pricing methods theoretically guide adjustment thoughts of sales price and solve the practical problems in our life.展开更多
In the paper some new upper bounds with parameters were obtained for the classical Ramsey numbers R(m,n,l) and R(m,n,l,s) . By using the upper bounds, it was proved that R (4,4,4)≤236.
Let K_(1,k)be a star of order k+1 and K_(n)■K_(1,k)the graph obtained from a complete graph K_(n)and an additional vertex v by joining v to k vertices of K_(n).For graphs G and H,the star-critical Ramsey number r_(*)...Let K_(1,k)be a star of order k+1 and K_(n)■K_(1,k)the graph obtained from a complete graph K_(n)and an additional vertex v by joining v to k vertices of K_(n).For graphs G and H,the star-critical Ramsey number r_(*)(G,H)is the minimum integer k such that any red/blue edge-coloring of K_(r-1)■K_(1,k)contains a red copy of G or a blue copy of H,where r is the classical Ramsey number R(G,H).Let C_(m)denote a cycle of order m and W_(n)a wheel of order n+1.Hook(2010)proved that r_(*)(W_(n),C_3)=n+3 for n≥6.In this paper,we show that r_(*)(W_(n),C_(m))=n+3 for m odd,m≥5 and n≥3(m-1)/2+2.展开更多
A method is put forward to establish the lower hounds for some n-color classical Ramsey numbersR(q,q,…,q) = Rn(q). With this method six new explicit lower bounds R4 (4) ≥458, R3(5)3≥242, R3(6)≥ 1070, R3(7)≥ 1214,...A method is put forward to establish the lower hounds for some n-color classical Ramsey numbersR(q,q,…,q) = Rn(q). With this method six new explicit lower bounds R4 (4) ≥458, R3(5)3≥242, R3(6)≥ 1070, R3(7)≥ 1214, R3(8)≥2834and R3(9)≥ 5282 are obtained using a computer.展开更多
Given a graph G and a positive integer k,define the Gallai–Ramsey number to be the minimum number of vertices n such that any k-edge coloring of Kn contains either a rainbow(all different colored)triangle or a monoch...Given a graph G and a positive integer k,define the Gallai–Ramsey number to be the minimum number of vertices n such that any k-edge coloring of Kn contains either a rainbow(all different colored)triangle or a monochromatic copy of G.In this paper,we obtain exact values of the Gallai–Ramsey numbers for the union of two stars in many cases and bounds in other cases.This work represents the first class of disconnected graphs to be considered as the desired monochromatic subgraph.展开更多
We report the recent advance in our rubidium atomic fountain clock（AFC）. The parameters of the Ramsey cavity are optimized by balancing the coupling from the two ports. The temperature control system of the Ramsey i...We report the recent advance in our rubidium atomic fountain clock（AFC）. The parameters of the Ramsey cavity are optimized by balancing the coupling from the two ports. The temperature control system of the Ramsey interaction region is renovated, and the resonant temperature of the Ramsey cavity is regulated to be slightly above the room temperature.The quality of magnetic environment in the Ramsey interaction region is also improved. A new digital-to-analog converter（DAC） circuit that controls the local oscillator is adopted to decrease the noise of the oven-controlled crystal oscillator output. As a result, the short-term fractional frequency stability of 2.7 × 10^-13τ^-1/2τand the long-term fractional frequency stability of 1.6 × 10^-15 at the average time of 32800 s are achieved.展开更多
In contrast to the overlapping-generations model, it is allowable to discount the future utility in a dynasty model without the ethical difficulty related to intergenerational conflicts. Much precedent research uses R...In contrast to the overlapping-generations model, it is allowable to discount the future utility in a dynasty model without the ethical difficulty related to intergenerational conflicts. Much precedent research uses Ramsey-type optimal growth theory in order to estimate the social discount rate. However, one must note that almost all the formulations neglect the existence of negative intertemporal externalities. This problem is vital when one analyzes the global warming problem mainly caused by the excess concentration of carbon dioxide (CO<sub>2</sub>). This is because an adjoining effect of capital accumulation exists besides the improvement of product capacity, which is reflected in the rate of interest (or equivalently, the marginal productivity of capital). That is, one cannot neglect a negative externality to the future productivity that originates from the excess emissions of CO<sub>2</sub>. Accordingly, following the optimal growth theory, the effective social discount rate should be heightened by a proportional carbon tax to suppress future excess consumption/ emissions than in the case of the existing analyses, which exclude such an intertemporal external diseconomy.展开更多
The Ramsey rule is regarded as a convenient vehicle for estimating the social discount rate in general. Carbon pricing is treated as another theory of environmental economics. This study clarifies the theoretical rela...The Ramsey rule is regarded as a convenient vehicle for estimating the social discount rate in general. Carbon pricing is treated as another theory of environmental economics. This study clarifies the theoretical relationship between the Ramsey rule and optimal carbon price, which has been overlooked in the existing research. It succeeds in deriving the optimal carbon price from the modified Ramsey rule in stationary state. Since the Ramsey rule decides the dynamics of an economy and a stationary state is its destination, by using the optimization condition of individual who are assumed to live infinitesimally short life, we can solve the optimal carbon price at stationary state.展开更多
We briefly introduce the connection between the Shannon capacity of a communication channel and graph Ramsey number, which may receive attention from researchers on communication theory and graph theory.
基金supported in part by National Natural Science Foundation of China (No.11931002)China Postdoctoral Science Foundation (No.2021M701162)。
文摘Given two graphs G and H,the Ramsey number R(G,H) is the minimum integer N such that any two-coloring of the edges of K_(N) in red or blue yields a red G or a blue H.Let v(G) be the number of vertices of G and χ(G) be the chromatic number of G.Let s(G) denote the chromatic surplus of G,the number of vertices in a minimum color class among all proper χ(G)-colorings of G.Burr showed that R(G,H)≥(v(G)-1)(χ(H)-1)+s(H) if G is connected and v(G)≥s(H).A connected graph G is H-good if R(G,H)=(v(G)-1)(χ(H)-1)+s(H).Let tH denote the disjoint union of t copies of graph H,and let G∨H denote the join of G and H.Denote a complete graph on n vertices by K_(n),and a tree on n vertices by T_(n).Denote a book with n pages by B_(n),i.e.,the join K_(2) ∨■.Erd?s,Faudree,Rousseau and Schelp proved that T_(n) is B_(m)-good if n≥3m-3.In this paper,we obtain the exact Ramsey number of T_(n) versus 2B_(2).Our result implies that T_(n) is 2B_(2)-good if n≥5.
基金supported in part by National Natural Science Foundation of China(Grant No.11931002)the Department of Education of Guangdong Province Natural Science Foundation(Grant No.2020KTSCX078)the Project of Hanshan Normal University(Grant No.QN202024).
文摘For an integer r≥2 and bipartite graphs Hi,where 1≤i≤r,the bipartite Ramsey number br(H1,H2,…,Hr)is the minimum integer N such that any r-edge coloring of the complete bipartite graph KN;N contains a monochromatic subgraph isomorphic to Hi in color i for some 1≤i≤r.We show that if r≥3;α1,α2>0,αj+2≥[(j+2)!-1]Σi=1^(j+1)α1 for j=1,2…r-2,then br(C2[α1n],C2[α2n],…,C2[αrn]=(Σ=j=1^(r)a j+o(1))n.
文摘We present a detailed analysis of phase sensitivity for a nonlinear Ramsey interferometer, which utilize effective mean-field interaction of a two-component Bose-Einstein condensate in phase ac- cumulation. For large enough particle number N and small phase shift φ, analytical results of the Ramsey signal and the phase sensitivity are derived for a product coherent state θ, 0）. When collisional dephasing is absent, we confirm that the optimal sensitivity scales as 2/N3/2 for polar angle of the initial state θ = π/4 or 3π/4. The best-sensitivity phase satisfies different transcendental equations, depending upon the initial state and the observable being measured after the phase accumulation. In the presence of the collisional dephasing, we show that the N-3/2-scaling rule of the sensitivity maintains with spin operators jx and jy measurements. A slightly better sensitivity is attainable for optimal coherent state with θ = π/6 or 5π/6.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFA0306600)Anhui Initiative in Quantum Information Technologies(Grant No.AHY050000)+1 种基金supported by the National Natural Science Foundation of China(Grant No.11905218)the CAS Key Laboratory for Research in Galaxies and Cosmology,Chinese Academy of Sciences(Grant No.18010203)。
文摘Herein,we propose a novel strategy for implementing a direct readout of the symmetric characteristic function of the quantum states of quantum fields without the involvement of idealized measurements,an aspect that has always been deemed ill-defined in quantum field theory.This proposed scheme relies on the quantum control and measurements of an auxiliary qubit locally coupled to the quantum fields.By mapping the expectation values of both the real and imaginary parts of the field displacement operator to the qubit states,the qubit's readout provides complete information regarding the symmetric characteristic function.We characterize our technique by applying it to the Kubo-Martin-Schwinger(thermal)and squeezed states of a quantum scalar field.In addition,we have discussed general applications of this approach to analogue-gravity systems,such as Bose-Einstein condensates,within the scope of state-of-the-art experimental capabilities.This proposed strategy may serve as an essential in understanding and optimizing the control of quantum fields for relativistic quantum information applications,particularly in exploring the interplay between gravity and quantum,for example,the relation to locality,causality,and information.
文摘The Ramsey number is a foundational result in combinatorics. This article will introduce Ramsey number with the method of graph theory, and the Ramsey pricing theory is applied to the sales price and study of cross subsidy. Based on the status of our sales price and cross subsidy, Ramsey pricing methods theoretically guide adjustment thoughts of sales price and solve the practical problems in our life.
文摘In the paper some new upper bounds with parameters were obtained for the classical Ramsey numbers R(m,n,l) and R(m,n,l,s) . By using the upper bounds, it was proved that R (4,4,4)≤236.
基金supported by the National Natural Science Foundation of China(Nos.11871270,12161141003,11931006)。
文摘Let K_(1,k)be a star of order k+1 and K_(n)■K_(1,k)the graph obtained from a complete graph K_(n)and an additional vertex v by joining v to k vertices of K_(n).For graphs G and H,the star-critical Ramsey number r_(*)(G,H)is the minimum integer k such that any red/blue edge-coloring of K_(r-1)■K_(1,k)contains a red copy of G or a blue copy of H,where r is the classical Ramsey number R(G,H).Let C_(m)denote a cycle of order m and W_(n)a wheel of order n+1.Hook(2010)proved that r_(*)(W_(n),C_3)=n+3 for n≥6.In this paper,we show that r_(*)(W_(n),C_(m))=n+3 for m odd,m≥5 and n≥3(m-1)/2+2.
基金Project supported by Guangxi Natural Science Foundation.
文摘A method is put forward to establish the lower hounds for some n-color classical Ramsey numbersR(q,q,…,q) = Rn(q). With this method six new explicit lower bounds R4 (4) ≥458, R3(5)3≥242, R3(6)≥ 1070, R3(7)≥ 1214, R3(8)≥2834and R3(9)≥ 5282 are obtained using a computer.
基金Supported by the National Science Foundation of China(Grant Nos.12061059 and 61763041)。
文摘Given a graph G and a positive integer k,define the Gallai–Ramsey number to be the minimum number of vertices n such that any k-edge coloring of Kn contains either a rainbow(all different colored)triangle or a monochromatic copy of G.In this paper,we obtain exact values of the Gallai–Ramsey numbers for the union of two stars in many cases and bounds in other cases.This work represents the first class of disconnected graphs to be considered as the desired monochromatic subgraph.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61275204 and 91336105)
文摘We report the recent advance in our rubidium atomic fountain clock（AFC）. The parameters of the Ramsey cavity are optimized by balancing the coupling from the two ports. The temperature control system of the Ramsey interaction region is renovated, and the resonant temperature of the Ramsey cavity is regulated to be slightly above the room temperature.The quality of magnetic environment in the Ramsey interaction region is also improved. A new digital-to-analog converter（DAC） circuit that controls the local oscillator is adopted to decrease the noise of the oven-controlled crystal oscillator output. As a result, the short-term fractional frequency stability of 2.7 × 10^-13τ^-1/2τand the long-term fractional frequency stability of 1.6 × 10^-15 at the average time of 32800 s are achieved.
文摘In contrast to the overlapping-generations model, it is allowable to discount the future utility in a dynasty model without the ethical difficulty related to intergenerational conflicts. Much precedent research uses Ramsey-type optimal growth theory in order to estimate the social discount rate. However, one must note that almost all the formulations neglect the existence of negative intertemporal externalities. This problem is vital when one analyzes the global warming problem mainly caused by the excess concentration of carbon dioxide (CO<sub>2</sub>). This is because an adjoining effect of capital accumulation exists besides the improvement of product capacity, which is reflected in the rate of interest (or equivalently, the marginal productivity of capital). That is, one cannot neglect a negative externality to the future productivity that originates from the excess emissions of CO<sub>2</sub>. Accordingly, following the optimal growth theory, the effective social discount rate should be heightened by a proportional carbon tax to suppress future excess consumption/ emissions than in the case of the existing analyses, which exclude such an intertemporal external diseconomy.
文摘The Ramsey rule is regarded as a convenient vehicle for estimating the social discount rate in general. Carbon pricing is treated as another theory of environmental economics. This study clarifies the theoretical relationship between the Ramsey rule and optimal carbon price, which has been overlooked in the existing research. It succeeds in deriving the optimal carbon price from the modified Ramsey rule in stationary state. Since the Ramsey rule decides the dynamics of an economy and a stationary state is its destination, by using the optimization condition of individual who are assumed to live infinitesimally short life, we can solve the optimal carbon price at stationary state.
基金This work was jointly supported by the National Natural Science Foundation of China (Grant No. 19871023) Education Minislry of China (Grant No. 2000-11) the "333" Foundation of Jiangsu Province and the Natural Science Foundation of Jiangsu Province(G
文摘We briefly introduce the connection between the Shannon capacity of a communication channel and graph Ramsey number, which may receive attention from researchers on communication theory and graph theory.
