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Professor Adam Letchford

Professor

  1. 2012
  2. Published

    Binary positive semidefinite matrices and associated integer polytopes

    Letchford, A. N. & Sorensen, M. M., 02/2012, In: Mathematical Programming. 131, 1-2, p. 253-271 19 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  3. Published

    Complexity results for the gap inequalities for the max-cut problem

    Galli, L., Kaparis, K. & Letchford, A. N., 05/2012, In: Operations Research Letters. 40, 3, p. 149-152 4 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  4. Published

    Fast bounding procedures for large instances of the simple plant location problem

    Letchford, A. N. & Miller, S. J., 05/2012, In: Computers and Operations Research. 39, 5, p. 985-990 6 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  5. 2013
  6. Published

    Compact formulations of the Steiner traveling salesman problem and related problems

    Letchford, A. & Nasiri, S. D., 2013, In: European Journal of Operational Research. 228, 1, p. 83-92 10 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  7. Published

    Computing upper bounds for the stable set problem using Lagrangian relaxation

    Letchford, A., 05/2013.

    Research output: Contribution to conference - Without ISBN/ISSN Conference paperpeer-review

  8. Published

    Approximating the Lovász θ function with the subgradient method

    Giandomenico, M., Letchford, A. N., Rossi, F. & Smriglio, S., 5/06/2013, In: Electronic Notes in Discrete Mathematics. 41, p. 157-164 8 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  9. Published

    A polyhedral approach to the single row facility layout problem

    Amaral, A. R. S. & Letchford, A., 10/2013, In: Mathematical Programming. 141, 1-2, p. 453-477 25 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  10. 2014
  11. Published

    Iterated Chvatal-Gomory cuts and the geometry of numbers

    Aliev, I. & Letchford, A., 2014, In: SIAM Journal on Optimization. 24, 3, p. 1294-1312 19 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  12. Published

    Pricing routines for vehicle routing with time windows on road networks

    Letchford, A. & Nasiri, S. D., 2014, Lancaster University: The Department of Management Science, 20 p. (Lancaster University Management School Working Paper Series; vol. 2014, no. 2).

    Research output: Working paper

  13. Published

    A dynamic programming heuristic for the quadratic knapsack problem

    Djeumou Fomeni, F. & Letchford, A., 02/2014, In: INFORMS Journal on Computing. 26, 1, p. 173-182 10 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  14. Published

    Unbounded convex sets for non-convex mixed-integer quadratic programming

    Burer, S. & Letchford, A., 1/02/2014, In: Mathematical Programming. 143, 1-2, p. 231-256 26 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  15. Published

    A compact variant of the QCR method for quadratically constrained quadratic 0-1 programs

    Galli, L. & Letchford, A., 04/2014, In: Optimization Letters. 8, 4, p. 1213-1224 12 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  16. Published

    An aggressive reduction scheme for the simple plant location problem

    Letchford, A. & Miller, S., 1/05/2014, In: European Journal of Operational Research. 234, 3, p. 674-682 9 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  17. Published

    A new separation algorithm for the Boolean quadric and cut polytopes

    Letchford, A. & Sorensen, M. M., 2/08/2014, In: Discrete Optimization. 14, p. 61-71 11 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  18. Published

    Pricing routines for vehicle routing with time windows on road networks

    Letchford, A., Nasiri, S. D. & Oukil, A., 11/2014, In: Computers and Operations Research. 51, p. 331-337 7 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  19. 2015
  20. Published

    Cutting planes for RLT relaxations of mixed 0-1 polynomial programs

    Djeumou Fomeni, F., Kaparis, K. & Letchford, A., 2015, In: Mathematical Programming. 151, 2, p. 639–658 20 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  21. Published

    Preface: The 2013 Newton Institute programme on polynomial optimisation

    Letchford, A., Lasserre, J. B., Parrilo, P. A. & Steurer, D., 07/2015, In: Mathematical Programming. 151, 2, p. 375–377 3 p.

    Research output: Contribution to Journal/MagazineEditorialpeer-review

  22. Published

    Ellipsoidal relaxations of the stable set problem: theory and algorithms

    Giandomenico, M., Letchford, A., Rossi, F. & Smriglio, S., 1/08/2015, In: SIAM Journal on Optimization. 25, 3, p. 1944-1963 20 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  23. Published

    Stronger multi-commodity flow formulations of the capacitated vehicle routing problem

    Letchford, A. & Salazar Gonzalez, J. J., 1/08/2015, In: European Journal of Operational Research. 244, 3, p. 730-738 9 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  24. Published

    The Steiner travelling salesman problem with correlated costs

    Letchford, A. & Nasiri, S., 16/08/2015, In: European Journal of Operational Research. 245, 1, p. 62–69 8 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  25. Published

    Review of "Integer Programming” by Conforti et al.

    Letchford, A. & Marecek, J., 1/10/2015, In: Interfaces. 45, 5, p. 481-482 2 p.

    Research output: Contribution to Journal/MagazineBook/Film/Article reviewpeer-review

  26. 2016
  27. Published

    Stronger multi-commodity flow formulations of the (capacitated) sequential ordering problem

    Letchford, A. & Salazar Gonzalez, J. J., 16/05/2016, In: European Journal of Operational Research. 251, 1, p. 74-84 11 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  28. Published

    Some hard combinatorial optimisation problems from mobile wireless communications

    Letchford, A. N., 18/05/2016. 2 p.

    Research output: Contribution to conference - Without ISBN/ISSN Conference paperpeer-review

  29. Published

    Strengthening Chvátal-Gomory cuts for the stable set problem

    Letchford, A. N., Marzi, F., Rossi, F. & Smriglio, S., 10/09/2016, Combinatorial Optimization: 4th International Symposium, ISCO 2016, Vietri sul Mare, Italy, May 16-18, 2016, Revised Selected Papers. Cerulli, R., Fujishige, S. & Mahjoub, A. R. (eds.). Berlin: Springer, p. 201-212 12 p. (Lecture Notes in Computer Science; vol. 9849).

    Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSNChapter (peer-reviewed)peer-review

  30. Published

    NATCOR: Ten years of doctoral training in OR

    Letchford, A., 15/12/2016, IFORS Newsletter, 10, 4, p. 10-11 2 p.

    Research output: Contribution to specialist publicationContribution to a Specialist Magazine - With ISSNpeer-review

  31. 2017
  32. Published

    On the Lovász theta function and some variants

    Galli, L. & Letchford, A. N., 27/07/2017, In: Discrete Optimization. 25, p. 159-174 16 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  33. Published

    An exact algorithm for a resource allocation problem in mobile wireless communications

    Letchford, A. N., Ni, Q. & Zhong, Z., 09/2017, In: Computational Optimization and Applications. 68, 2, p. 193-208 16 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  34. Published

    A note on representations of linear inequalities in non-convex mixed-integer quadratic programs

    Letchford, A. N. & Grainger, D., 6/11/2017, In: Operations Research Letters. 45, 6, p. 631-634 4 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  35. Published

    Projection results for the k-partition problem

    Fairbrother, J. & Letchford, A. N., 8/11/2017, In: Discrete Optimization. 26, p. 97-111 15 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  36. 2018
  37. Published

    A sum-of-squares approach to achieving fairness in combinatorial optimisation

    Letchford, A., 04/2018.

    Research output: Contribution to conference - Without ISBN/ISSN Conference paperpeer-review

  38. Published

    A two-level graph partitioning problem arising in mobile wireless communications

    Fairbrother, J., Letchford, A. N. & Briggs, K., 04/2018, In: Computational Optimization and Applications. 69, 3, p. 653-676 24 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  39. Published

    A note on the 2-circulant inequalities for the max-cut problem

    Kaparis, K. & Letchford, A. N., 07/2018, In: Operations Research Letters. 46, 4, p. 443-447 5 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  40. Published

    Bi-perspective cuts for mixed-integer fractional programs with indicator variables

    Letchford, A., 07/2018.

    Research output: Contribution to conference - Without ISBN/ISSN Conference paperpeer-review

  41. Published

    A heuristic for maximising energy efficiency in OFDMA systems with QoS constraints

    Letchford, A. N., Ni, Q. & Zhong, Z., 1/07/2018, Combinatorial Optimization: 5th International Symposium. Lee, J., Rinaldi, G. & Mahjoub, A. R. (eds.). Springer, p. 303-312 10 p. (Lecture Notes in Computer Science; vol. 10856).

    Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSNChapter (peer-reviewed)peer-review

  42. Published

    A binarisation heuristic for non-convex quadratic programming with box constraints

    Galli, L. & Letchford, A. N., 1/09/2018, In: Operations Research Letters. 46, 5, p. 529-533 5 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  43. Published

    New valid inequalities and facets for the simple plant location problem

    Galli, L., Letchford, A. N. & Miller, S., 16/09/2018, In: European Journal of Operational Research. 269, 3, p. 824-833 10 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  44. Published

    A guide to conic optimisation and its applications

    Letchford, A. N. & Parkes, A. J., 11/2018, In: RAIRO Operations Research. 52, 4, p. 1087-1106 20 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  45. 2019
  46. Published

    The capacitated vehicle routing problem: stronger bounds in pseudo-polynomial time

    Letchford, A. N. & Salazar Gonzalez, J. J., 1/01/2019, In: European Journal of Operational Research. 272, 1, p. 24–31 8 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  47. Published

    On lifted cover inequalities: a new lifting procedure with unusual properties

    Letchford, A. N. & Souli, G., 17/01/2019, In: Operations Research Letters. 47, 2, p. 83-88 6 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  48. Published

    Detecting changes in slope with an L0 penalty

    Fearnhead, P., Maidstone, R. & Letchford, A., 1/06/2019, In: Journal of Computational and Graphical Statistics. 28, 2, p. 265-275 11 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  49. Published

    Convex hulls for mixed-integer quadratic programs with bounded variables

    Letchford, A., 09/2019.

    Research output: Contribution to conference - Without ISBN/ISSN Conference paperpeer-review

  50. Published

    New valid inequalities for the fixed-charge and single-node flow polytopes

    Letchford, A. & Souli, G., 1/09/2019, In: Operations Research Letters. 47, 5, p. 353-357 5 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  51. 2020
  52. Published

    A heuristic for fair dynamic resource allocation in over-loaded OFDMA systems

    Letchford, A., Ni, Q. & Zhong, Z., 1/02/2020, In: Journal of Heuristics. 26, 1, p. 21-32 12 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  53. Published

    Valid inequalities for mixed-integer programmes with fixed charges on sets of variables

    Letchford, A. & Souli, G., 1/05/2020, In: Operations Research Letters. 48, 3, p. 240-244 5 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  54. Published

    Adaptive policies for perimeter surveillance problems

    Grant, J. A., Leslie, D. S., Glazebrook, K., Szechtman, R. & Letchford, A., 16/05/2020, In: European Journal of Operational Research. 283, 1, p. 265-278 14 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  55. Published

    Using ℓp-norms for fairness in combinatorial optimisation

    Bektas, T. & Letchford, A., 1/08/2020, In: Computers and Operations Research. 120, 11 p., 104975.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  56. Published

    Lifting the knapsack cover inequalities for the knapsack polytope

    Letchford, A. & Souli, G., 1/09/2020, In: Operations Research Letters. 48, 5, p. 607-611 5 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  57. Published

    On matroid parity and matching polytopes

    Kaparis, K., Letchford, A. & Mourtos, I., 30/09/2020, In: Discrete Applied Mathematics. 284, p. 322-331 10 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  58. Published

    The stable set problem: clique and nodal inequalities revisited

    Letchford, A., Rossi, F. & Smriglio, S., 30/11/2020, In: Computers and Operations Research. 123, 16 p., 105024.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  59. 2021
  60. Published

    Facets from gadgets

    Letchford, A. & Vu, A., 1/01/2021, In: Mathematical Programming. 185, 1-2, p. 297-314 18 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  61. Published

    Vehicle routing on road networks: how good is Euclidean approximation?

    Boyacı, B., Dang, T. & Letchford, A., 1/05/2021, In: Computers and Operations Research. 129, 13 p., 105197.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  62. Published

    A separation algorithm for the simple plant location problem

    Galli, L. & Letchford, A., 31/07/2021, In: Operations Research Letters. 49, 4, p. 610-615 6 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  63. Published

    On the complexity of surrogate and group relaxation for integer linear programs

    Dokka, T., Letchford, A. & Mansoor, H., 31/07/2021, In: Operations Research Letters. 49, 4, p. 530-534 5 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  64. Published

    Strengthened clique-family inequalities for the stable set polytope  

    Letchford, A. & Ventura, P., 31/07/2021, In: Operations Research Letters. 49, 4, p. 586-589 4 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  65. Published

    Maths of OR – Reflections from the Committee

    Fliege, J., Letchford, A. & Tilley, D., 1/08/2021, Mathematics Today, 57, 4, p. 115 1 p.

    Research output: Contribution to specialist publicationArticle

  66. Published

    Valid inequalities for quadratic optimisation with domain constraints

    Galli, L. & Letchford, A., 31/08/2021, In: Discrete Optimization. 41, 19 p., 100661.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  67. Published

    Biperspective functions for mixed-integer fractional programs with indicator variables

    Letchford, A., Ni, Q. & Zhong, Z., 30/11/2021, In: Mathematical Programming. 190, 1-2, p. 39-55 17 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  68. 2022
  69. Published

    On matchings, T-joins and arc routing problems

    Boyacı, B., Dang, T. & Letchford, A., 31/01/2022, In: Networks. 79, 1, p. 20-31 12 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  70. Published

    Generalised 2-circulant inequalities for the max-cut problem

    Kaparis, K., Letchford, A. & Mourtos, I., 31/03/2022, In: Operations Research Letters. 50, 2, p. 122-128 7 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  71. Published

    The Boolean quadric polytope

    Letchford, A., 1/05/2022, The Quadratic Unconstrained Binary Optimization Problem: Theory, Algorithms, and Applications. Punnen, A. (ed.). Cham, Switzerland: Springer, p. 97-120 24 p.

    Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSNChapter (peer-reviewed)peer-review

  72. Published

    A cut-and-branch algorithm for the quadratic knapsack problem

    Djeumou Fomeni, F., Kaparis, K. & Letchford, A., 31/05/2022, In: Discrete Optimization. 44, 2, 18 p., 100579.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  73. Published

    Newsvendor problems: An integrated method for estimation and optimisation

    Liu, C., Letchford, A. & Svetunkov, I., 16/07/2022, In: European Journal of Operational Research. 300, 2, p. 590-601 12 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  74. Published

    On the multiple knapsack assignment problem

    Letchford, A., 08/2022.

    Research output: Contribution to conference - Without ISBN/ISSN Conference paperpeer-review

  75. Published

    Revisiting surrogate relaxation for the multidimensional knapsack problem

    Dokka, T., Letchford, A. & Mansoor, H., 30/11/2022, In: Operations Research Letters. 50, 6, p. 674-678 5 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  76. 2023
  77. Published

    Fast upper and lower bounds for a large-scale real-world arc routing problem

    Boyacı, B., Dang, T. & Letchford, A., 31/01/2023, In: Networks. 81, 1, p. 107-124 18 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  78. Published

    Improving a constructive heuristic for the general routing problem

    Boyacı, B., Dang, T. & Letchford, A., 31/01/2023, In: Networks. 81, 1, p. 93-106 14 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  79. Published

    On upper bounds for the multiple knapsack assignment problem

    Letchford, A., 04/2023.

    Research output: Contribution to conference - Without ISBN/ISSN Conference paperpeer-review

  80. Published

    The mathematics of operational research

    Letchford, A., Liu, K., Misener, R., Syntetos, A. & Tilley, D., 1/08/2023, Mathematics Today, 69, 4, p. 103 1 p.

    Research output: Contribution to specialist publicationArticle

  81. Published

    The 4th IMA and OR Society conference on the mathematics of operational research: thoughts from the committee

    Tilley, D., Letchford, A., Syntetos, A., Misener, R. & Liu, K., 1/09/2023, IFORS Newsletter, 18, 3, p. 35-37 3 p.

    Research output: Contribution to specialist publicationContribution to a Specialist Magazine - With ISSNpeer-review

  82. Published

    A survey on exact algorithms for the maximum flow and minimum-cost flow problems

    Cruz Mejía, O. & Letchford, A., 30/09/2023, In: Networks. 82, 2, p. 167-176 10 p.

    Research output: Contribution to Journal/MagazineReview articlepeer-review

  83. Published

    Matheuristics: survey and synthesis

    Boschetti, M., Letchford, A. & Maniezzo, V., 30/11/2023, In: International Transactions in Operational Research. 30, 6, p. 2840-2866 27 p.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  84. Published

    On cut polytopes and graph minors

    Kaparis, K., Letchford, A. & Mourtos, I., 30/11/2023, In: Discrete Optimization. 50, 100807.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  85. Published

    On some lower bounds for the permutation flowshop problem

    Letchford, A., Dang, T. & Caceres Gelvez, S., 30/11/2023, In: Computers and Operations Research. 159, 9 p., 106320.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  86. 2024
  87. Published

    Arc routing problems

    Eglese, R. & Letchford, A., 10/02/2024, Encyclopedia of Optimization. Pardalos, P. & Prokopyev, O. (eds.). 3rd ed. Cham: Springer, 6 p.

    Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSNEntry for encyclopedia/dictionary

  88. Published

    CP-Lib: Benchmark instances of the clique partitioning problem

    Sorensen, M. & Letchford, A., 1/03/2024, In: Mathematical Programming Computation. 16, 1, p. 93-111 19 p., 1.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  89. Published

    Operational research: methods and applications

    Petropoulos, F., Laporte, G., Archetti, C., Ayhan, H., Battarra, M., Bennell, J. A., Boylan, J. E., Breton, M., Canca, D., Charlin, L., Chen, B., Cicek, C. T., Jr, L. A. C., Currie, C. S. M., Demeulemeester, E., Ding, L., Disney, S. M., Ehrgott, M., Eppler, M. J. & Erdoğan, G. & 59 others, Fortz, B., Franco, L. A., Frische, J., Greco, S., Gregory, A. J., Hämäläinen, R. P., Herroelen, W., Hewitt, M., Holmström, J., Hooker, J. N., Işık, T., Johnes, J., Kara, B. Y., Karsu, Ö., Kent, K., Köhler, C., Kunc, M., Kuo, Y.-H., Lienert, J., Letchford, A. N., Leung, J., Li, D., Li, H., Ljubić, I., Lodi, A., Lozano, S., Lurkin, V., Martello, S., McHale, I. G., Midgley, G., Morecroft, J. D. W., Mutha, A., Oğuz, C., Petrovic, S., Pferschy, U., Psaraftis, H. N., Rose, S., Saarinen, L., Salhi, S., Song, J.-S., Sotiros, D., Stecke, K. E., Strauss, A. K., Tarhan, İ., Thielen, C., Toth, P., Berghe, G. V., Vasilakis, C., Vaze, V., Vigo, D., Virtanen, K., Wang, X., Weron, R., White, L., Woensel, T. V., Yearworth, M., Yıldırım, E. A., Zaccour, G. & Zhao, X., 1/03/2024, In: Journal of the Operational Research Society. 75, 3, p. 423-617 195 p.

    Research output: Contribution to Journal/MagazineReview articlepeer-review

  90. Published

    On upper bounds for the multiple knapsack assignment problem

    Galli, L. & Letchford, A., 1/05/2024, In: Operations Research Letters. 54, 6 p., 107104.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  91. Published

    On a variant of the change-making problem

    Letchford, A. & Cheng, L., 30/11/2024, In: Operations Research Letters. 57, 3 p., 107165.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  92. 2025
  93. Published

    New facets of the clique partitioning polytope

    Letchford, A. & Soerensen, M., 6/03/2025, In: Operations Research Letters. 59, 4 p., 107242.

    Research output: Contribution to Journal/MagazineJournal articlepeer-review

  94. Forthcoming

    On a hierarchy of polytopes for integer quadratic programming

    Galli, L. & Letchford, A., 8/05/2025, (Accepted/In press) Mathematics, Algorithms and the Art and Science of Decision-Making. Barbato, M., Bianchessi, N. & Boggio Tomasaz, A. (eds.). Springer

    Research output: Contribution in Book/Report/Proceedings - With ISBN/ISSNChapter (peer-reviewed)peer-review

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