19,049 research outputs found
Early quantum task scheduling
An Early Quantum Task (EQT) is a Quantum EDF task that has shrunk its first period into one quantum time slot. Its purpose is to be executed as soon as possible, without causing deadline overflow of other tasks. We will derive the conditions under which an EQT can be admitted and can have an immediate start. The advantage of scheduling EQTs is shown by its use in a buffered multi-media server. The EQT is associated with a multimedia stream and it will use its first invocation to fill the buffer, such that a client can start receiving data immediately
The Sequential Order of Procedural Instructions: Some Formal Methods for Designers of Flow Charts
Document designers who present procedural instructions can choose several formats: prose, table, logical tree, or flow chart. In all cases, however, it is essential that the instructions are ordered in a way that allows users to reach the outcome in as little time as possible. In this article two formal methods are discussed that help determine which order is most efficient. The first method is based on the selection principle. The second method is based on the principle of the average least effort
The Right Mutation Strength for Multi-Valued Decision Variables
The most common representation in evolutionary computation are bit strings.
This is ideal to model binary decision variables, but less useful for variables
taking more values. With very little theoretical work existing on how to use
evolutionary algorithms for such optimization problems, we study the run time
of simple evolutionary algorithms on some OneMax-like functions defined over
. More precisely, we regard a variety of
problem classes requesting the component-wise minimization of the distance to
an unknown target vector . For such problems we see a crucial
difference in how we extend the standard-bit mutation operator to these
multi-valued domains. While it is natural to select each position of the
solution vector to be changed independently with probability , there are
various ways to then change such a position. If we change each selected
position to a random value different from the original one, we obtain an
expected run time of . If we change each selected position
by either or (random choice), the optimization time reduces to
. If we use a random mutation strength with probability inversely proportional to and change
the selected position by either or (random choice), then the
optimization time becomes , bringing down
the dependence on from linear to polylogarithmic. One of our results
depends on a new variant of the lower bounding multiplicative drift theorem.Comment: an extended abstract of this work is to appear at GECCO 201
A Positive Analysis of Targeted Employment Protection Legislation
In many countries, Employment Protection Legislation (EPL) establishes less strict dismissal procedures for specific groups of workers. This paper builds a simple matching model with heterogeneous workers in order to analyze this feature of EPL. We use the model to analyze the effects of reforms targeted at lowering the firing costs of a particular group of workers, and compare the results with those stemming from a comprehensive reform that reduces firing costs for all workers. The model is calibrated for the Spanish economy, where an important reform of this kind took place in 1997. Overall, our results point out that EPL reforms achieve the largest reduction in unemployment when they are targeted to workers with lower and more volatile productivity.Publicad
Non-perturbative renormalization of moments of parton distribution functions
We compute non-perturbatively the evolution of the twist-2 operators
corresponding to the average momentum of non-singlet quark densities. The
calculation is based on a finite-size technique, using the Schr\"odinger
Functional, in quenched QCD. We find that a careful choice of the boundary
conditions, is essential, for such operators, to render possible the
computation. As a by-product we apply the non-perturbatively computed
renormalization constants to available data of bare matrix elements between
nucleon states.Comment: Lattice2003(Matrix); 3 pages, 3 figures. Talk by A.
Locality with staggered fermions
We address the locality problem arising in simulations, which take the square
root of the staggered fermion determinant as a Boltzmann weight to reduce the
number of dynamical quark tastes. A definition of such a theory necessitates an
underlying local fermion operator with the same determinant and the
corresponding Green's functions to establish causality and unitarity. We
illustrate this point by studying analytically and numerically the square root
of the staggered fermion operator. Although it has the correct weight, this
operator is non-local in the continuum limit. Our work serves as a warning that
fundamental properties of field theories might be violated when employing
blindly the square root trick. The question, whether a local operator
reproducing the square root of the staggered fermion determinant exists, is
left open.Comment: 24 pages, 7 figures, few remarks added for clarity, accepted for
publication in Nucl. Phys.
A MATCHING MODEL OF CROWDING-OUT AND ON-THE- JOB SEARCH (WITH AN APPLICATION TO SPAIN)
This paper considers a matching model of heterogenous and jobs which includes on-the-job search. High-educated workers transitorily accept unskilled jobs and continue to search for skilled jobs. We study the implications of this model for the unemployment rates of high and low-educated workers, for the share of mismatched workers and wage nequality both within and between skill groups. The model is used to shed light on the Spanish experience following a large educational upgrading since the mid-eighties.
- …