Abstract
Convexification based on convex envelopes is ubiquitous in the non-linear optimization literature. Thanks to considerable efforts of the optimization community for decades, we are able to compute the convex envelopes of a considerable number of functions that appear in practice, and thus obtain tight and tractable approximations to challenging problems. We contribute to this line of work by considering a family of functions that, to the best of our knowledge, has not been considered before in the literature. We call this family ray-concave functions. We show sufficient conditions that allow us to easily compute closed-form expressions for the convex envelope of ray-concave functions over arbitrary polytopes. With these tools, we are able to provide new perspectives to previously known convex envelopes and derive a previously unknown convex envelope for a function that arises in probability contexts.
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Notes
A function is polyhedral if its epigraph is a polyhedron.
References
Al-Khayyal, F.A., Falk, J.E.: Jointly constrained biconvex programming. Math. Oper. Res. 8(2), 273–286 (1983). https://doi.org/10.1287/moor.8.2.273
Anstreicher, K.M., Burer, S.: Computable representations for convex hulls of low-dimensional quadratic forms. Math. Program. 124(1), 33–43 (2010). https://doi.org/10.1007/s10107-010-0355-9
Bao, X., Sahinidis, N.V., Tawarmalani, M.: Multiterm polyhedral relaxations for nonconvex, quadratically constrained quadratic programs. Optim. Methods Softw. 24(4–5), 485–504 (2009). https://doi.org/10.1080/10556780902883184
Benson, H.P.: On the construction of convex and concave envelope formulas for bilinear and fractional functions on quadrilaterals. Comput. Optim. Appl. 27(1), 5–22 (2004). https://doi.org/10.1023/B:COAP.0000004976.52180.7f
Hijazi, H.: Perspective envelopes for bilinear functions. In: AIP Conference Proceedings, vol. 2070, p. 020017. AIP Publishing LLC (2019)
Inc., W.R.: Mathematica, Version 12.3.1. Champaign, IL (2021). https://www.wolfram.com/mathematica
Jach, M., Michaels, D., Weismantel, R.: The convex envelope of (n-1)-convex functions. SIAM J. Optim. 19(3), 1451–1466 (2008). https://doi.org/10.1137/07069359X
Jensen, J.L.W.V.: Om konvekse funktioner og uligheder imellem middelvaerdier. Nyt tidsskrift for matematik 16, 49–68 (1905)
Khajavirad, A., Michalek, J.J., Sahinidis, N.V.: Relaxations of factorable functions with convex-transformable intermediates. Math. Program. 144(1), 107–140 (2014). https://doi.org/10.1007/s10107-012-0618-8
Khajavirad, A., Sahinidis, N.V.: Convex envelopes of products of convex and component-wise concave functions. J. Glob. Optim. 52(3), 391–409 (2012). https://doi.org/10.1007/s10898-011-9747-5
Khajavirad, A., Sahinidis, N.V.: Convex envelopes generated from finitely many compact convex sets. Math. Program. 137(1), 371–408 (2013). https://doi.org/10.1007/s10107-011-0496-5
Kuno, T.: A branch-and-bound algorithm for maximizing the sum of several linear ratios. J. Glob. Optim. 22(1), 155–174 (2002). https://doi.org/10.1023/A:1013807129844
Li, Y.C., Yeh, C.C.: Some characterizations of convex functions. Comput. Math. Appl. 59(1), 327–337 (2010). https://doi.org/10.1016/j.camwa.2009.05.020
Liberti, L., Pantelides, C.C.: Convex envelopes of monomials of odd degree. J. Glob. Optim. 25(2), 157–168 (2003). https://doi.org/10.1023/A:1021924706467
Linderoth, J.: A simplicial branch-and-bound algorithm for solving quadratically constrained quadratic programs. Math. Program. 103(2), 251–282 (2005). https://doi.org/10.1007/s10107-005-0582-7
Locatelli, M.: Polyhedral subdivisions and functional forms for the convex envelopes of bilinear, fractional and other bivariate functions over general polytopes. J. Glob. Optim. 66(4), 629–668 (2016). https://doi.org/10.1007/s10898-016-0418-4
Locatelli, M.: Convex envelopes of bivariate functions through the solution of KKT systems. J. Glob. Optim. 72(2), 277–303 (2018). https://doi.org/10.1007/s10898-018-0626-1
Locatelli, M.: Convex envelope of bivariate cubic functions over rectangular regions. J. Glob. Optim. 76(1), 1–24 (2020). https://doi.org/10.1007/s10898-019-00846-2
Locatelli, M., Schoen, F.: On convex envelopes for bivariate functions over polytopes. Math. Program. 144(1), 65–91 (2014). https://doi.org/10.1007/s10107-012-0616-x
Luedtke, J., Namazifar, M., Linderoth, J.: Some results on the strength of relaxations of multilinear functions. Math. Program. 136(2), 325–351 (2012). https://doi.org/10.1007/s10107-012-0606-z
McCormick, G.P.: Computability of global solutions to factorable nonconvex programs: part I—convex underestimating problems. Math. Program. 10(1), 147–175 (1976). https://doi.org/10.1007/BF01580665
Meyer, C.A., Floudas, C.A.: Trilinear monomials with mixed sign domains: facets of the convex and concave envelopes. J. Glob. Optim. 29(2), 125–155 (2004). https://doi.org/10.1023/B:JOGO.0000042112.72379.e6
Meyer, C.A., Floudas, C.A.: Convex envelopes for edge-concave functions. Math. Program. 103(2), 207–224 (2005). https://doi.org/10.1007/s10107-005-0580-9
Muller, B., Serrano, F., Gleixner, A.: Using two-dimensional projections for stronger separation and propagation of bilinear terms. SIAM J. Optim. 30(2), 1339–1365 (2020). https://doi.org/10.1137/19M1249825
Rikun, A.D.: A convex envelope formula for multilinear functions. J. Glob. Optim. 10(4), 425–437 (1997). https://doi.org/10.1023/A:1008217604285
Ryoo, H.S., Sahinidis, N.V.: Analysis of bounds for multilinear functions. J. Glob. Optim. 19(4), 403–424 (2001). https://doi.org/10.1023/A:1011295715398
Satyanarayana, A., Wood, R.K.: A linear-time algorithm for computing k-terminal reliability in series-parallel networks. SIAM J. Comput. 14(4), 818–832 (1985). https://doi.org/10.1137/0214057
Sherali, H.D.: Convex envelopes of multilinear functions over a unit hypercube and over special discrete sets. Acta Math. Vietnam 22(1), 245–270 (1997)
Sherali, H.D., Alameddine, A.: An explicit characterization of the convex envelope of a bivariate bilinear function over special polytopes. Ann. Oper. Res. 25(1), 197–209 (1990). https://doi.org/10.1007/BF02283695
Tardella, F.: On the existence of polyhedral convex envelopes. In: Floudas, C.A., Pardalos, P. (eds.) Frontiers in Global Optimization, pp. 563–573. Springer, Berlin (2004). https://doi.org/10.1007/978-1-4613-0251-3_30
Tardella, F.: Existence and sum decomposition of vertex polyhedral convex envelopes. Optim. Lett. 2(3), 363–375 (2008). https://doi.org/10.1007/s11590-007-0065-2
Tawarmalani, M., Richard, J.P.P., Xiong, C.: Explicit convex and concave envelopes through polyhedral subdivisions. Math. Program. 138(1), 531–577 (2013). https://doi.org/10.1007/s10107-012-0581-4
Tawarmalani, M., Sahinidis, N.V.: Semidefinite relaxations of fractional programs via novel convexification techniques. J. Glob. Optim. 20(2), 133–154 (2001). https://doi.org/10.1023/A:1011233805045
Zamora, J.M., Grossmann, I.E.: A branch and contract algorithm for problems with concave univariate, bilinear and linear fractional terms. J. Glob. Optim. 14(3), 217–249 (1999). https://doi.org/10.1023/A:1008312714792
Acknowledgements
The research leading to these results received funding from grants ANID/CONICYT-Fondecyt Regular 1200809 (J.B., E.M.), MathAmsud 19-MATH-03 (J.B.) and ANID/CONICYT-Fondecyt Iniciación 11190515 (G.M.). We would also like to thank Felipe Serrano for helpful discussions and to the anonymous reviewer for their valuable feedback.
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Barrera, J., Moreno, E. & Muñoz, G. Convex envelopes for ray-concave functions. Optim Lett 16, 2221–2240 (2022). https://doi.org/10.1007/s11590-022-01852-2
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DOI: https://doi.org/10.1007/s11590-022-01852-2