Some aspects of (r,k)-parking functions

An \emph{$(r,k)$-parking function} of length $n$ may be defined as a sequence $(a_1,\dots,a_n)$ of positive integers whose increasing rearrangement $b_1\leq\cdots\leq b_n$ satisfies $b_i\leq k+(i-1)r$. The case $r=k=1$ corresponds to ordinary parking functions. We develop numerous properties of $(r,k)$-parking functions. In particular, if $F_n^{(r,k)}$ denotes the Frobenius characteristic of the action of the symmetric group $\mathfrak{S}_n$ on the set of all $(r,k)$-parking functions of length $n$, then we find a combinatorial interpretation of the coefficients of the power series $\left( \sum_{n\geq 0}F_n^{(r,1)}t^n\right)^k$ for any $k\in \mathbb{Z}$. When $k>0$, this power series is just $\sum_{n\geq 0} F_n^{(r,k)} t^n$; when $k<0$, we obtain a dual to $(r,k)$-parking functions. We also give a $q$-analogue of this result. For fixed $r$, we can use the symmetric functions $F_n^{(r,1)}$ to define a multiplicative basis for the ring $\Lambda$ of symmetric functions. We investigate some of the properties of this basis

The Surf Clam ITQ Management: An Evaluation

Environmental Economics and Policy, Resource /Energy Economics and Policy,

A Large Deviation Rate and Central Limit Theorem for Horton Ratios

Although originating in hydrology, the classical Horton analysis is based on a geometric progression that is widely used in the empirical analysis of branching patterns found in biology, atmospheric science, plant pathology, etc., and more recently in tree register allocation in computer science. The main results of this paper are a large deviation rate and a central limit theorem for Horton bifurcation ratios in a standard network model. The methods are largely self-contained. In particular, derivations of some previously known results of the theory are indicated along the way

Essentially non-oscillatory shock capturing methods applied to turbulence amplification in shock wave calculations

ENO (essentially non-oscillatory) schemes can provide uniformly high order accuracy right up to discontinuities while keeping sharp, essentially non-oscillatory shock transitions. Recently, an efficient implementation of ENO schemes was obtained based on fluxes and TVD Runge-Kutta time discretizations. The resulting code is very simple to program for multi-dimensions. ENO schemes are especially suitable for computing problems with both discontinuities and fine structures in smooth regions, such as shock interaction with turbulence, for which results for 1-D and 2-D Euler equations are presented. Much better resolution is observed by using third order ENO schemes than by using second order TVD schemes for such problems

A unified approach to polynomial sequences with only real zeros

We give new sufficient conditions for a sequence of polynomials to have only real zeros based on the method of interlacing zeros. As applications we derive several well-known facts, including the reality of zeros of orthogonal polynomials, matching polynomials, Narayana polynomials and Eulerian polynomials. We also settle certain conjectures of Stahl on genus polynomials by proving them for certain classes of graphs, while showing that they are false in general.Comment: 19 pages, Advances in Applied Mathematics, in pres

An Econometric Model for American Lobster

An econometric model for the wholesale and ex-vessel markets of American lobster, Homarus amedcanus, was developed to determine the market impact of proposed increases in the minimum size for American lobster. Prices were found to be inflexible with respect to landing, imports, and income (i.e., the price flexibilities were less than one) in both wholesale and ex-vessel markets. The size of lobster has a statistically significant effect on wholesale and ex-vessel prices and revenues. On average, wholesalers pass along 52% of any price changes to lobstermen. The ex-vessel price impact of a given change in supply is about the same as for changes in either landings or imports. Any changes in public policies leading to increases in total landings of American lobster and/or decreases in the proportion of small lobsters in the landings would result in increases in gross revenues to fishermen and wholesalers. While the long-term impact would be favorable, the short-term market impact of increases in the minimum size for lobster would be uncertain.Demand and Price Analysis, Environmental Economics and Policy, Resource /Energy Economics and Policy,