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Miguel Anjos, PhD, FCAE, FEUROPT, SMIEEE

QAPLIB is a Quadratic Assignment Problem Library.


Four previously unsolved QAPLIB instances have been solved to optimality in recent years: see tai30a, tai35b, tai40b, and sko42.


We present below the 28 instances that have not yet been solved to optimality; recent developments are highlighted. Have you found a better solution or bound? Send me an email!

Thonemann and Bölte (1994)

Feasible

solution

Bound

Gap

Tho40 (n = 40)

240516

226490

5.83%

Tho150 (n = 150)

8133398

7620628

6.30%

Wilhelm and Ward (1987)

Feasible

solution

Bound

Gap

Wil50 (n = 50)

48816

48121

1.42%

Wil100 (n = 100)

273038

268955

1.50%

Taillard (1991, 1995)

Feasible

solution

Bound

Gap

Software

Tai35a (n = 35)

2422002

2216627

8.48%


Tai40a (n = 40)

3139370

2843274

9.43%


Tai50a (n = 50)

4938796

4390920

11.09%


Tai50b (n = 50)

458821517

431090700

6.04%


Tai60a (n = 60)

7205962

6325978

12.21%


Tai60b (n = 60)

608215054

592371800

2.60%


Tai80a (n = 80)

13499184

11657010

13.65%


Tai80b (n = 80)

818415043

786298800

3.92%


Tai100a (n = 100)

21044752

17853840

15.16%


Tai100b (n = 100)

1185996137

2.15%

Tai150b (n = 150)

498896643

5.12%

Tai256c (n = 256)

44759294

44095032

1.48%


Skorin-Kapov (1990)

Feasible

solution

Bound

Gap

Software

Sko49 (n = 49)

23386

22650

3.15%


Sko56 (n = 56)

34458

33385

 3.11%


Sko64 (n = 64)

48498

47017

3.05%


Sko72 (n = 72)

66256

64455

3.05%


Sko81 (n = 81)

90998

88359

2.90%


Sko90 (n = 90)

115534

112423

2.69%


Sko100a (n = 100)

152002

2.65%

Sko100b (n = 100)

153890

2.76%

Sko100c (n = 100)

147862

2.50%

Sko100d (n = 100)

149576

2.82%

Sko100e (n = 100)

149150

2.62%

Sko100f (n = 100)

149036

2.87%

0