Semistrict models of connected 3-types and Tamsamani's weak 3-groupoids

Homotopy 3-types can be modelled algebraically by Tamsamani's weak 3-groupoids as well as, in the path-connected case, by cat^2-groups. This paper gives a comparison between the two models in the path-connected case. This leads to two different semistrict algebraic models of connected 3-types using the Tamsamani's model. Both are then related to Gray groupoids.Comment: 21 page

(Co)homology of crossed modules with coefficients in a π1\pi_1-module

We define a cotriple (co)homology of crossed modules with coefficients in a $\pi_1$-module. We prove its general properties, including the connection with the existing cotriple theories on crossed modules. We establish the relationship with the (co)homology of the classifying space of a crossed module and with the cohomology of groups with operators. An example and an application are given.Comment: 32 pages, LaTeX2e, Paul Taylor's diagram package; added reference. Accepted for publication by Homology, Homotopy and Application

Is a Technological Singularity near also for bots in MMOGs?

Using the idea of the Technological Singularity this essay offers some reflections on the possible future of bots in Massively Multiplayer Online Games (MMOGs). The paper starts by briefly introducing the notion of Technological Singularity as the advent of a super-intelligent Artificial Intelligence that could threaten human existence. Bots are computer programs that automate repetitive and time consuming activities for the Internet user. In MMOGs, bots are often used to cheat and could have nefarious effects on the gameplay. Assuming that bots are rudimentary forms of Artificial Intelligence that also pose a threat to MMOGs and their players, the paper presents some evidence-based trends of the future evolution of bots and the implications of these for Virtual Worlds research

Some energy conservative schemes for vibro-impacts of a beam on rigid obstacles

Caused by the problem of unilateral contact during vibrations of satellite solar arrays, the aim of this paper is to better understand such a phenomenon. Therefore, it is studied here a simplified model composed by a beam moving between rigid obstacles. Our purpose is to describe and compare some families of fully discretized approximations and their properties, in the case of non-penetration Signorini’s conditions. For this, starting from the works of Dumont and Paoli, we adapt to our beam model the singular dynamic method introduced by Renard. A particular emphasis is given in the use of a restitution coefficient in the impact law. Finally, various numerical results are presented and energy conservation capabilities of the schemes are investigated

Global existence result for phase transformations with heat transfer in shape memory alloys

We consider three-dimensional models for rate-independent processes describing materials undergoing phase transformations with heat transfer. The problem is formulated within the framework of generalized standard solids by the coupling of the momentum equilibrium equation and the flow rule with the heat transfer equation. Under appropriate regularity assumptions on the initial data, we prove the existence a global solution for this thermodynamically consistent system, by using a fixed-point argument combined with global energy estimates

The Weakly Globular Double Category of Fractions of a Category

This paper introduces the construction of a weakly globular double category of fractions for a category and studies its universal properties. It shows that this double category is locally small and considers a couple of concrete examples.Comment: 73 pages. arXiv admin note: substantial text overlap with arXiv:1210.405