On the bounded generation of arithmetic SL2{\rm SL}_2

Let $K$ be a number field and ${\mathcal O}$ be the ring of $S$-integers in $K$. Morgan, Rapinchuck, and Sury have proved that if the group of units ${\mathcal O}^{\times}$ is infinite, then every matrix in ${\rm SL}_2({\mathcal O})$ is a product of at most $9$ elementary matrices. We prove that under the additional hypothesis that $K$ has at least one real embedding or $S$ contains a finite place we can get a product of at most $8$ elementary matrices. If we assume a suitable Generalized Riemann Hypothesis, then every matrix in ${\rm SL}_2({\mathcal O})$ is the product of at most $5$ elementary matrices if $K$ has at least one real embedding, the product of at most $6$ elementary matrices if $S$ contains a finite place, and the product of at most $7$ elementary matrices in general

Bailouts in Costa Rica as a Result of Government Centralization and Discretionary Transfers

This paper investigates the inter-relation between the central government and the municipalities in Costa Rica. It examines episodes in which the central government has bailed out the local governments from their obligations. We employ empirical and descriptive methods to show how discretionary grants relate to the degree of fiscal discipline of the municipality to produce hidden bailouts. Political, demographic, and economic variables explain the allocation of these discretionary transfers. We illustrate the effects of the high concentration of decision-making of the central government on the fiscal performance of the municipalities. The municipalities play a limited role and its functioning largely depends upon the central government. We argue that the national administration would face a high political cost if it did not bail out the local government in several of the episodes studied. Using panel data from 1982-1997 on 81 cantones, we find that the fiscal effort of the local government is reduced by the presence of discretionary grants. The local governments finance local expenses with these discretionary transfers according to our empirical results. As expected from the centralization issue, political variables such as the affiliation of the local administration have significant effects on the resources received by the municipalities.

Seasonal movements in short-term yield spreads

An abstract for this article is not availableTreasury bills

Economic consequences of tax simplification

Tax reform ; Taxation

Term structure puzzles

Interest rates