BASBLib - A Library of Bilevel Test Problems

A growing collection of bilevel problems

Linear-Nonlinear bilevel problem from [Mitsos & Barton, 2007]

Optimal solution

Objective values Solution point(s)
F* = -0.800 x* = 0.000
f* = 0.000 y* = -0.800

Illustration of the problem

Outer Problem Inner Problem

Description in the AMPL format

var x >= -1, <= 1;          # Outer variables
var y >= -0.8, <= 1;        # Inner variables
var l{1..2} >= 0, <= 100;   # KKT Multipliers

minimize outer_obj: y;      # Outer objective

subject to
# Inner objective:
    inner_obj: x*(16*y^4 + 2*y^3 - 8*y^2 - 1.5*y + 0.5) = 0;
# KKT conditions:
    stationarity:      x*(64*y^3 + 6*y^2 - 16*y - 1.5) - l[1] + l[2] = 0;
    complementarity_1: l[1]*(-0.8 - y) = 0;
    complementarity_2: l[2]*(y - 1) = 0;

References