Zitterbewegung and reduction: 4D spinning particles and 3D anyons on light-like curves

We construct the model with light-like world-lines for the massive 4D spinning particles and 3D anyons. It is obtained via the formal bosonization of pseudoclassical model for the massive Dirac particle with subsequent reduction to the light-like curves. The peculiarity of the light-like trajectories produced due to the Zitterbewegung is explained from the viewpoint of reduction and reparametrization invariance.Comment: 10 pages, discussion expanded and references added. To appear in Phys. Lett.

Resonances in a spring-pendulum: algorithms for equivariant singularity theory

A spring-pendulum in resonance is a time-independent Hamiltonian model system for formal reduction to one degree of freedom, where some symmetry (reversibility) is maintained. The reduction is handled by equivariant singularity theory with a distinguished parameter, yielding an integrable approximation of the Poincaré map. This makes a concise description of certain bifurcations possible. The computation of reparametrizations from normal form to the actual system is performed by Gröbner basis techniques.

Household credit to the poor and its impact on child schooling in peri-urban areas, Vietnam

This paper uses a novelty dataset of poor households in peri-urban areas in Vietnam to estimate impacts of small loans on child schooling. The Probit and Negative Binomial model estimates roughly indicate no strong evidence of the effect, especially of informal credit. Formal credit is likely to have positive impacts on child schooling, but its effect is not strong enough to be conclusive. The paper suggests that to obtain the target of sustainable poverty reduction, easing access to formal credit sources as well as exempting tuition and other school fees are necessary to keep poor children at schools longer

Approximate symmetry reduction approach: infinite series reductions to the KdV-Burgers equation

For weak dispersion and weak dissipation cases, the (1+1)-dimensional KdV-Burgers equation is investigated in terms of approximate symmetry reduction approach. The formal coherence of similarity reduction solutions and similarity reduction equations of different orders enables series reduction solutions. For weak dissipation case, zero-order similarity solutions satisfy the Painlev\'e II, Painlev\'e I and Jacobi elliptic function equations. For weak dispersion case, zero-order similarity solutions are in the form of Kummer, Airy and hyperbolic tangent functions. Higher order similarity solutions can be obtained by solving linear ordinary differential equations.Comment: 14 pages. The original model (1) in previous version is generalized to a more extensive form and the incorrect equations (35) and (36) in previous version are correcte

Model Checking Paxos in Spin

We present a formal model of a distributed consensus algorithm in the executable specification language Promela extended with a new type of guards, called counting guards, needed to implement transitions that depend on majority voting. Our formalization exploits abstractions that follow from reduction theorems applied to the specific case-study. We apply the model checker Spin to automatically validate finite instances of the model and to extract preconditions on the size of quorums used in the election phases of the protocol.Comment: In Proceedings GandALF 2014, arXiv:1408.556

International Conflict, Defense Spending and the Size of Countries

This paper provides a formal model of endogenous country formation and of choice of defense spending in a world with international conflict. The model is consistent with three observations. First, secessions and, more generally, break-up of countries should follow a reduction in the likelihood of international conflict. Second, the number of regional conflicts between smaller countries may increase as a result of the break-up of larger countries. Third, the size of the peace divided -- i.e., the reduction in the defense spending in a more peaceful world -- is limited by the process of country break-up.

Amalgamation of Transition Sequences in the PEPA Formalism

This report presents a proposed formal approach towards reduction of sequences in PEPA components. By performing the described amalgamation procedure we may remove, from the Markov chain underlying an initial PEPA model, those states for which detailed local balance equations cannot be formulated. This transformation may lead to a simpler model with product form solution. Some classes of reduced models preserve those performance measures which we are interested in and, moreover, the steady state solution vector is much easier to find from the computational point of view