83,131 research outputs found

    Two conjectures in Ramsey-Tur\'an theory

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    Given graphs H1,,HkH_1,\ldots, H_k, a graph GG is (H1,,Hk)(H_1,\ldots, H_k)-free if there is a kk-edge-colouring ϕ:E(G)[k]\phi:E(G)\rightarrow [k] with no monochromatic copy of HiH_i with edges of colour ii for each i[k]i\in[k]. Fix a function f(n)f(n), the Ramsey-Tur\'an function RT(n,H1,,Hk,f(n))\textrm{RT}(n,H_1,\ldots,H_k,f(n)) is the maximum number of edges in an nn-vertex (H1,,Hk)(H_1,\ldots,H_k)-free graph with independence number at most f(n)f(n). We determine RT(n,K3,Ks,δn)\textrm{RT}(n,K_3,K_s,\delta n) for s{3,4,5}s\in\{3,4,5\} and sufficiently small δ\delta, confirming a conjecture of Erd\H{o}s and S\'os from 1979. It is known that RT(n,K8,f(n))\textrm{RT}(n,K_8,f(n)) has a phase transition at f(n)=Θ(nlogn)f(n)=\Theta(\sqrt{n\log n}). However, the values of RT(n,K8,o(nlogn))\textrm{RT}(n,K_8, o(\sqrt{n\log n})) was not known. We determined this value by proving RT(n,K8,o(nlogn))=n24+o(n2)\textrm{RT}(n,K_8,o(\sqrt{n\log n}))=\frac{n^2}{4}+o(n^2), answering a question of Balogh, Hu and Simonovits. The proofs utilise, among others, dependent random choice and results from graph packings.Comment: 20 pages, 2 figures, 2 pages appendi

    Quantum Random Number Generator using Photon-Number Path Entanglement

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    We report a novel quantum random number generator based on the photon-number-path entangled state which is prepared via two-photon quantum interference at a beam splitter. The randomness in our scheme is of truly quantum mechanical origin as it comes from the projection measurement of the entangled two-photon state. The generated bit sequences satisfy the standard randomness test

    THE COST-EFFECTIVENESS OF ALTERNATIVE EMISSION CONTROL POLICIES IN THE SAN JOAQUIN VALLEY OF CALIFORNIA

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    This study analyzes the ROG control costs of stationary sources in the San Joaquin Valley of California. The cost-effectiveness of market incentive approaches such as an uniform marketable permit system, localized marketable permit system and an ambient permit system as well as a traditional command-and-control approach are examined.Environmental Economics and Policy,
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