BASBLib - A Library of Bilevel Test Problems

A growing collection of bilevel problems

Quadratic-Quadratic bilevel problem from [Tuy et al., 2007]


Optimal solution

Objective values Solution points
F* = 22.5 x* = 1.5
f* = -4.5 y* = 4.5

Sources where this problem occurs

Original source:

Other sources:

Description of the problem in the AMPL format

var x >= 0, <= 10;         # Outer variable
var y >= 0, <= 10;         # Inner variable
var l{1..5} >= 0, <= 10;   # KKT Multipliers

minimize outer_obj: x^2 + y^2;  # Outer objective

subject to
# Inner objective:
    inner_obj: -y = 0;
# Inner constraints
    inner_con1:     3*x + y - 15 <= 0;
    inner_con2:     x + y - 7 <= 0;
    inner_con3:     x + 3*y - 15 <= 0;
# KKT conditions:
    stationarity:      -1 + l[1] + l[2] + 3*l[3] - l[4] + l[5] = 0;
    complementarity_1: l[1]*(3*x + y - 15) = 0;
    complementarity_2: l[2]*(x + y - 7) = 0;
    complementarity_3: l[3]*(x + 3*y - 15) = 0;
    complementarity_4: l[4]*y = 0;
    complementarity_5: l[5]*(y - 10) = 0;

References