Toroidal and Klein bottle boundary slopes

Let M be a compact, connected, orientable, irreducible 3-manifold and T' an incompressible torus boundary component of M such that the pair (M,T') is not cabled. By a result of C. Gordon, if S and T are incompressible punctured tori in M with boundary on T' and boundary slopes at distance d, then d is at most 8, and the cases where d=6,7,8 are very few and classified. We give a simplified proof of this result (or rather, of its reduction process), based on an improved estimate for the maximum possible number of mutually parallel negative edges in the graphs of intersection of S and T. We also extend Gordon's result by allowing either S or T to be an essential Klein bottle. to the case where S or T is a punctured essential Klein bottle.Comment: Preliminary version, updated. We use a new approach that yields a stronger conclusion. 28 pages, 18 figure

Interest Groups and Trade Reform in Mexico

Mexico experienced widespread economic reform in the last two decades. From being a protectionist economy with a policy of import substitution, it has turned into an export-oriented open economy. Why was protectionism a stable policy, and how was it overturned by a reform that went against entrenched interests? I apply a game theoretic model of political influence and economic reform to answer these questions using data to calculate the payoffs for the relevant interest groups. In the underlying cooperative game, the core is empty and a protectionist coalition of import-substituting firms and the government was "stable" until the eighties. Adjusting the model's parameters to changes in the government's financing options in the late eighties and early nineties leads to a different and unique outcome. In the predicted outcome a free trade policy is adopted through cooperation between all players.Trade Reform, Mexico, Coalition Formation, Aspirations, Cooperative Games, Interest Groups

A Theory of Political Influence and Economic Organization

I propose a cooperative game theory model of economic reform in a political environment with interest groups. Agents in a better economic position have strategic advantage in formulating economic policy. Agents bargain over policies because they are associated with different income distributions. In this context I examine the robustness of the `Coase Theorem' prediction of efficient bargaining. I use the Aspiration Core and the Aspiration Bargaining Set as solutions to the cooperative game. Even under zero transaction costs, if endogenous coalition formation is allowed, bargaining between interest groups need not result in efficient economic change because the core may be empty. Indeed, I show that there are inefficient equilibrium outcomes if and only if the core is empty.Political Economy, Interest Groups, Institutional Change, Coalition Formation, Cooperative Games, Aspiration Solution Concepts

Solutions without dummy axiom for TU cooperative games

In this paper we study an expression for all additive, symmetric and efficient solutions, i.e., the set of axioms that traditionally are used to characterize the Shapley value except for the dummy axiom. Also, we obtain an expression for this kind of solutions by including the self duality axiom. These expressions allow us to give an alternative formula for the consensus value, the generalized consensus value and the solidarity solution. Furthermore, we introduce a new axiom called coalitional independence which replaces the symmetry axiom and use it to get similar results.axiomatic characterization

Universality and Non-Perturbative Definitions of 2D Quantum Gravity from Matrix Models

The universality of the non-perturbative definition of Hermitian one-matrix models following the quantum, stochastic, or $d=1$-like stabilization is discussed in comparison with other procedures. We also present another alternative definition, which illustrates the need of new physical input for $d=0$ matrix models to make contact with 2D quantum gravity at the non-perturbative level.Comment: 20 page