Backwards-induction outcome in a quantum game

In economics duopoly is a market dominated by two firms large enough to influence the market price. Stackelberg presented a dynamic form of duopoly that is also called `leader-follower' model. We give a quantum perspective on Stackelberg duopoly that gives a backwards-induction outcome same as the Nash equilibrium in static form of duopoly also known as Cournot's duopoly. We find two qubit quantum pure states required for this purpose.Comment: Revised in the light of referee's comments. Latex, 16 pages, 2 figures, To appear in Phy. Rev.

Simulation of continuous variable quantum games without entanglement

A simulation scheme of quantum version of Cournot's Duopoly is proposed, in which there is a new Nash equilibrium that may be also Pareto optimal without any entanglement involved. The unique property of this simulation scheme is decoherence-free against the symmetric photon loss. Furthermore, we analyze the effects of the asymmetric information on this simulation scheme and investigate the case of asymmetric game caused by asymmetric photon loss. A second-order phase transition-like behavior of the average profits of the firm 1 and firm 2 in Nash equilibrium can be observed with the change of the degree of asymmetry of the information or the degree of "virtual cooperation". It is also found that asymmetric photon loss in this simulation scheme plays a similar role with the asymmetric entangled states in the quantum game. PACS numbers: 02.50.Le, 03.67.-aComment: 7 pages, 4 figures, RevTex, some contents have been revise

Quantum mechanics gives stability to a Nash equilibrium

We consider a slightly modified version of the Rock-Scissors-Paper (RSP) game from the point of view of evolutionary stability. In its classical version the game has a mixed Nash equilibrium (NE) not stable against mutants. We find a quantized version of the RSP game for which the classical mixed NE becomes stable.Comment: Revised on referee's criticism, submitted to Physical Review

Quantum correlations and Nash equilibria of a bi-matrix game

Playing a symmetric bi-matrix game is usually physically implemented by sharing pairs of 'objects' between two players. A new setting is proposed that explicitly shows effects of quantum correlations between the pairs on the structure of payoff relations and the 'solutions' of the game. The setting allows a re-expression of the game such that the players play the classical game when their moves are performed on pairs of objects having correlations that satisfy the Bell's inequalities. If players receive pairs having quantum correlations the resulting game cannot be considered another classical symmetric bi-matrix game. Also the Nash equilibria of the game are found to be decided by the nature of the correlations.Comment: minor correction

Improving International Comparisons of Real Output: The ICP 2005 Benchmark and its Implications for China

The latest round of the International Comparisons Program (ICP 2005) compares the purchasing power of currencies and real output of 146 countries. Using price quote data from nine countries in the Asia-Pacific region, we consider ways of improving the methods used in ICP 2005 and new applications of these methods (e.g., for calculating rural-urban price differentials). The most striking result in ICP 2005 was that China came out 40 percent smaller than previously thought. We also evaluate the extent to which this finding can be attributed to excessive sampling of prices in China from urban areas or of unrepresentative products.International Comparisons Program; Country-Product-Dummy Method; Price Index; Basic Heading; Urban-Rural Price Differences; Representative and Unrepresentative Products; Asia-Pacific Region

Suitability of carbon nanotubes grown by chemical vapor deposition for electrical devices

Using carbon nanotubes (CNTs) produced by chemical vapor deposition, we have explored different strategies for the preparation of carbon nanotube devices suited for electrical and mechanical measurements. Though the target device is a single small diameter CNT, there is compelling evidence for bundling, both for CNTs grown over structured slits and on rigid supports. Whereas the bundling is substantial in the former case, individual single-wall CNTs (SWNTs) can be found in the latter. Our evidence stems from mechanical and electrical measurements on contacted tubes. Furthermore, we report on the fabrication of low-ohmic contacts to SWNTs. We compare Au, Ti and Pd contacts and find that Pd yields the best results.Comment: pdf including figures, see: http://www.unibas.ch/phys-meso/Research/Papers/2004/Suitability-CVD-tubes.pd

Flexible Spatial and Temporal Hedonic Price Indexes for Housing in the Presence of Missing Data

We propose a flexible hedonic methodology for computing house price indexes that uses multiple imputation (MI) to account for missing data (a huge problem in housing data sets). Ours is the first study to use MI in this context. We also allow for spatial correlation, include interaction terms between characteristics, between regions and periods, and between regions and characteristics, and break the regressions up into overlapping blocks of five consecutive periods (quarters in our case). These features ensure that the shadow prices are flexible both across regions and time. This flexible structure makes the derivation of price indexes from the estimated regression equations far from straightforward. We develop innovative methods for resolving this problem and for splicing the overlapping blocks together to generate the overall panel results. We then use our methodology to construct temporal and spatial price indexes for 15 regions in Sydney, Australia on a quarterly basis from 2001 to 2006 and combine them to obtain an overall price index for Sydney. Our hedonic indexes differ quite significantly from the official index for Sydney published by the Australian Bureau of Statistics. We also find clear evidence of convergence in prices across regions from 2001-3 (while prices were rising), and divergence thereafter. We conclude by exploring some of the implications of these empirical findings.Real estate; House prices; Hedonic price index; Missing data; Multiple imputation; Spatial correlation

Analysis of two-player quantum games in an EPR setting using geometric algebra

The framework for playing quantum games in an Einstein-Podolsky-Rosen (EPR) type setting is investigated using the mathematical formalism of Clifford geometric algebra (GA). In this setting, the players' strategy sets remain identical to the ones in the classical mixed-strategy version of the game, which is then obtained as proper subset of the corresponding quantum game. As examples, using GA we analyze the games of Prisoners' Dilemma and Stag Hunt when played in the EPR type setting.Comment: 20 pages, no figure, revise

The Refined Topological Vertex

We define a refined topological vertex which depends in addition on a parameter, which physically corresponds to extending the self-dual graviphoton field strength to a more general configuration. Using this refined topological vertex we compute, using geometric engineering, a two-parameter (equivariant) instanton expansion of gauge theories which reproduce the results of Nekrasov. The refined vertex is also expected to be related to Khovanov knot invariants.Comment: 70 Pages, 23 Figure