BASBLib - A Library of Bilevel Test Problems

A growing collection of bilevel problems

Quadratic-Quadratic bilevel problem from (Lucchetti et al., 1987)


Optimal solution

Objective values Solution point
F* = 0.0 x* = 1.0
f* = 0.0 y* = 0.0

Sources where this problem occurs

Original source:

Other sources:

Description of the problem in the AMPL format

var x >= 0, <= 1;         # Outer variables
var y >= 0, <= 1;         # Inner variables
var l{1..2} >= 0, <= 10;  # KKT Multipliers

minimize outer_obj: 0.5*(1-x) + x*y;

subject to
# Inner objective
    inner_obj: (x-1)*y = 0;
# KKT conditions
    stationarity:      x - 1 - l[1] + l[2] = 0;
    complementarity_1: l[1]*y = 0;
    complementarity_2: l[2]*(y - 1) = 0;

References