Gleb Belov

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Activity overview

Latest activity by Gleb Belov
  • Gleb Belov created a post,

    Branch-cut(-price) node LP warm start

    Hi, assume someone implements branch-and-cut... and needs to solve the LP relaxations in different nodes. This means, after solving the LP of one node, we can switch to a very different node (diffe...

  • Gleb Belov commented,

    Oh I think every constraint type has its own pool, there is no overall ordering of constraints. Resolved then.

  • Gleb Belov created a post,

    QCP duals

    Answered

    Hi, when retrieving duals of linear and quadratic constraints, I noticed that methods GRBgetdblattr(element) interpret the indices as the indices in the subset of only quadratic constraints, or, if...

  • Gleb Belov commented,

    Well I guess an alternative way is to have 2 opposite constraints (<=, >=). For the C API, this is the only 'official' way because GRBaddqconstr only documents GRB_LESS_EQUAL or GRB_GREATER_EQUAL, ...

  • Gleb Belov commented,

    A similar question for quadratic range constraints: is the extra slack variable the best way of modelling as well?

  • Gleb Belov commented,

    When providing LP warm start (C/VBASIS or P/DSTART) after GRBaddrangeconstr(), I receive ''Warning, invalid warm-start basis discarded" (printer 2x for some reason). Will this be fixed or the advic...

  • Gleb Belov commented,

    Hi Jaromił, the instance (recognized as convex quadratic, despite the equality) is this: MaximizeobjSubject Top_times_0: - obj + [ x ^2 ] = 0Boundsx <= 10obj <= 100End When I call gurobi_cl ResultF...

  • Gleb Belov created a post,

    ObjBoundC not available

    Answered

    Hi, when solving a simple quadratic model, Gurobi finishes at root node. Then, trying to retrieve ObjBoundC, we get Unable to retrieve attribute 'ObjBoundC'.Failed to get the best bound. Gurobi err...

  • Gleb Belov created a post,

    Exporting parameter list

    For a modeling system like MiniZinc it would be useful to see the list of parameters supported by the solver. There are functions in gurobi.h allowing access to the list and feasible/default values...

  • Gleb Belov commented,

    Hi Daniel, the advice that it should be that IntFeasTol >= FeasibilityTol appears more familiar to me but still I'd found it helpful to have it reminded in the descriptions of those parameters. Yes...