I consider the problem of estimating the effect of a health care reform on the frequency of individual doctor visits when the reform effect is potentially different in different parts of the outcome distribution. Quantile regression is a powerful method for studying such heterogeneous treatment effects. Only recently has this method been extended to situations where the dependent variable is a ...

in this paper, we develop a freight transportation model for railway network considering hazmat transportation issue. in the transportation system considered, different customers can request for carrying hazmat and non- hazmat boxes. it is assumed that the sequence of the trains in the network is known. the objective is assigning the non-hazmat boxes and hazmat boxes to wagons of the trains so ...

Familiarly, in Z, we have unique factorization. We investigate the general ring and what conditions we can impose on it to necessitate analogs of unique factorization. The trivial ideal structure of a field, the extent to which primary decomposition is unique, that a Noetherian ring necessarily has one, that a principal ideal domain is a unique factorization domain, and that a Dedekind domain h...

a one-sided ideal of a ring has the insertion of factors property (or simply, ifp) if implies r for . we say a one-sided ideal of has the weakly ifp if for each , implies , for some non-negative integer . we give some examples of ideals which have the weakly ifp but have not the ifp. connections between ideals of which have the ifp and related ideals of some ring extensions are also shown.

The topic of Gray codes for the set of compositions with non-negative integer parts has been studied by several authors. Klingsberg gave a non-recursive description of a Gray code for this set after the recursive version of Knuth. Recently, Walsh modified Klingsberg’s algorithm to find a Gray code which generates the set of all bounded compositions with non-negative integer parts. In this paper...

In this paper a new PID controller is presented. Its peculiarity consists in the non integer order of the derivative and integral, being this order variable in the range [0,1], and providing two further parameters to the controller. The key element is a Multi-layer Perceptron that evaluate a non integer order integration. The neural network approach allows to overcome some problems related to p...

Mixed-integer polynomial programming (MIPP) problems are one class of mixed-integer nonlinear programming (MINLP) problems where objective function and constraints are restricted to the polynomial functions. Although the MINLP problem is NP-hard, in special cases such as MIPP problems, an efficient algorithm can be extended to solve it. In this research, we propose an algorit...

Presented here is a generalization of the implicit enumeration algorithm that can be applied when the objec-tive function is being maximized and can be rewritten as the difference of two non-decreasing functions. Also developed is a computational algorithm, named linear speedup, to use whatever explicit linear constraints are present to speedup the search for a solution. The method is easy to u...