Due to the increased utilization of gas-fired combined-cycle units for power generation in the U.S., accurate and computationally efficient models are more and more needed. The recently proposed edge-based formulation for combinedcycle units helps accurately describe the operations of combinedcycle units including capturing the transition processes and physical constraints for each turbine. In ...

This paper presents our contribution to the SemEval-2014 shared task on BroadCoverage Semantic Dependency Parsing. We employ a feature-rich linear model, including scores for first and second-order dependencies (arcs, siblings, grandparents and co-parents). Decoding is performed in a global manner by solving a linear relaxation with alternating directions dual decomposition (AD3). Our system ac...

We study different extended formulations for the set X = {x ∈ Z | Ax = Ax} in order to tackle the feasibility problem for the set X+ = X ∩ Z+. Here the goal is not to find an improved polyhedral relaxation of conv(X+), but rather to reformulate in such a way that the new variables introduced provide good branching directions, and in certain circumstances permit one to deduce rapidly that the in...

In this section we consider another method for solving the set cover problem approximately. The method uses randomized rounding of the solution obtained from the linear programming (LP) relaxation of set cover. The basic idea behind this algorithm is first to solve the LP relaxation for the set cover problem. We can think of the solution ~x as a probability to either select a set or not. Note t...

Universal polytope is the polytope de ned as the convex hull of the characteristic vectors of all triangulations for a given point con guration. The equality system de ning this polytope was found, but the system of inequalities are not known yet. Larger polytopes, corresponding to linear programming relaxations, have been used in practice. We show that (1) the universal polytope, the polytope ...

Many numerical computations show an only small difference between the optimal value of the one-dimensional cutting stock problem and that of its corresponding linear programming relaxation. In this paper we investigate the one-dimensional cutting stock problem with respect to the modified integer round-up property (MIRUP) and present some results on subproblems having the MIRUP.

Objective(s): Relevance between magnetic resonance imaging (MRI) relaxation rate and concentration of magnetic nanoparticles determines the capability of a nanomaterial to provide MRI contrast. In the present study, alginate was conjugated to gadolinium/graphene oxide nanocomposite to form gadolinium/graphene oxide/alginate nanocomposite, aiming to investigate its effect on the relevance betwee...

Given a complete graph Kn = (V, E) with non-negative edge costs c ∈ R E , the problem 2EC is that of finding a 2-edge connected spanning multi-subgraph of Kn of minimum cost. The integrality gap α2EC of the linear programming relaxation 2EC LP for 2EC has been conjectured to be 6 5 , although currently we only know that 6 5 ≤ α2EC ≤ 3 2. In this paper, we explore the idea of using the structure...

The corner relaxation of a mixed-integer linear program is a central concept in cutting plane theory. In a recent paper Fischetti and Monaci provide an empirical assessment of the strength of the corner and other related relaxations on benchmark problems. In this paper we give a precise characterization of the bounds given by these relaxations for the edge formulation of the maximum stable set ...

The task of the train timetabling problem or track allocation problem is to find conflict free schedules for a set of trains with predefined routes in a railway network. Especially for nonperiodic instances models based on time expanded networks are often used. Unfortunately, the linear programming relaxation of these models is often extremely weak because these models do not describe combinato...