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,

    How does Gurobi compute the IIS for infeasible models with integer variables?

    From the article "How does Gurobi compute the IIS for infeasible models?" it is not clear what happens for non-convex models (although it is helpful as a starting point). Is there any public inform...

  • 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...