Rabia Nessah

The Minimization of the Weighted Completion Time Variance in a Single Machine: A Specialized Cutting-Plane Approach

  • Stefano Nasini
  • Rabia Nessah
    • Categories (Mixed) Integer Linear Programming, Branch and Cut Algorithms, Scheduling

    This study addresses the problem of minimizing the weighted completion time variance (WCTV) in single-machine scheduling. Unlike the unweighted version, which has been extensively studied, the weighted variant introduces unique challenges due to the absence of theoretical properties that could guide the design of efficient algorithms. We propose a mathematical programming framework based on a … Read more

    Nash Bargaining Partitioning in Decentralized Portfolio Management

  • Francisco Benita
  • Stefano Nasini
  • Rabia Nessah
    • Categories Finance and Economics, Game Theory, Stochastic Programming Tags , , , ,

    In the context of decentralized portfolio management, understanding how to distribute a fixed budget among decentralized intermediaries is a relevant question for financial investors. We consider the Nash bargaining partitioning for a class of decentralized investment problems, where intermediaries are in charge of the portfolio construction in heterogeneous local markets and act as risk/disutility minimizers. … Read more

    An Almost Exact Multi-Machine Scheduling Solution for Homogeneous Processing

  • Stefano Nasini
  • Rabia Nessah
    • Categories (Mixed) Integer Nonlinear Programming, Combinatorial Optimization, Scheduling

    In the context of job scheduling in parallel machines, we present a class of asymptotically exact binary programs for the minimization of the $\tau$-norm of completion time variances. Building on overlooked properties of the min completion time variance in a single machine and on an equivalent bilevel formulation, our approach provides an asymptotic approximation (with … Read more

    An Almost Exact Solution to the Min Completion Time Variance in a Single Machine

  • Stefano Nasini
  • Rabia Nessah
    • Categories 0-1 Programming, Combinatorial Optimization, Scheduling Tags , , ,

    We consider a single machine scheduling problem to minimize the completion time variance of n jobs. This problem is known to be NP-hard and our contribution is to establish a novel bounding condition for a characterization of an optimal sequence. Specifically, we prove a necessary and sufficient condition (which can be verified in O(n\log n)) … Read more

    Sufficient condition on Schrage conjecture about the completion time variance

  • Rabia Nessah
    • Categories Applications - OR and Management Sciences Tags , ,

    We consider a single machine scheduling problem to minimize the completion time variance. This roblem is known to be NP-hard. We prove that if $p_{n-1} = p_{n-2$, then there is an optimal solution of the form $(n,n-2,n-3,…,n-4,n-1)$. A new lower bound are proposed for solving the problem. The test on more than 4000 instances shows … Read more