100,572 research outputs found
Second-order optimality conditions for interval-valued functions
This work is included in the search of optimality conditions for solutions to the scalar
interval optimization problem, both constrained and unconstrained, by means of
second-order optimality conditions. As it is known, these conditions allow us to reject
some candidates to minima that arise from the first-order conditions. We will define
new concepts such as second-order gH-derivative for interval-valued functions,
2-critical points, and 2-KKT-critical points. We obtain and present new types of
interval-valued functions, such as 2-pseudoinvex, characterized by the property that
all their second-order stationary points are global minima. We extend the optimality
criteria to the semi-infinite programming problem and obtain duality theorems.
These results represent an improvement in the treatment of optimization problems
with interval-valued functions.Funding for open access publishing: Universidad de Cádiz/CBUA. The research has been supported by MCIN through
grant MCIN/AEI/PID2021-123051NB-I00
Optimal Predictive Eco-Driving Cycles for Conventional, Electric, and Hybrid Electric Cars
International audienceIn this paper, the computation of eco-driving cycles for electric, conventional and hybrid vehicles using receding horizon and optimal control is studied. The problem is formulated as consecutive-optimization problems aiming at minimizing the vehicle energy consumption under traffic and speed constraints. The impact of the look-ahead distance and the optimization frequency on the optimal speed computation is studied to find a trade-off between the optimality and the computation time of the algorithm. For the three architectures considered, simulation results show that in urban driving conditions, a look-ahead distance of 300m to 500m leads to a sub-optimality less than 1% in the energy consumption compared to the global solution. For highway driving conditions, a look-ahead distance of 1km to 1.5km leads to a sub-optimality less than 2% compared to the global solution
Global rates of convergence for nonconvex optimization on manifolds
We consider the minimization of a cost function on a manifold using
Riemannian gradient descent and Riemannian trust regions (RTR). We focus on
satisfying necessary optimality conditions within a tolerance .
Specifically, we show that, under Lipschitz-type assumptions on the pullbacks
of to the tangent spaces of , both of these algorithms produce points
with Riemannian gradient smaller than in
iterations. Furthermore, RTR returns a point where also the Riemannian
Hessian's least eigenvalue is larger than in
iterations. There are no assumptions on initialization.
The rates match their (sharp) unconstrained counterparts as a function of the
accuracy (up to constants) and hence are sharp in that sense.
These are the first deterministic results for global rates of convergence to
approximate first- and second-order Karush-Kuhn-Tucker points on manifolds.
They apply in particular for optimization constrained to compact submanifolds
of , under simpler assumptions.Comment: 33 pages, IMA Journal of Numerical Analysis, 201
Optimal Linear Precoding Strategies for Wideband Non-Cooperative Systems based on Game Theory-Part II: Algorithms
In this two-part paper, we address the problem of finding the optimal
precoding/multiplexing scheme for a set of non-cooperative links sharing the
same physical resources, e.g., time and bandwidth. We consider two alternative
optimization problems: P.1) the maximization of mutual information on each
link, given constraints on the transmit power and spectral mask; and P.2) the
maximization of the transmission rate on each link, using finite order
constellations, under the same constraints as in P.1, plus a constraint on the
maximum average error probability on each link. Aiming at finding decentralized
strategies, we adopted as optimality criterion the achievement of a Nash
equilibrium and thus we formulated both problems P.1 and P.2 as strategic
noncooperative (matrix-valued) games. In Part I of this two-part paper, after
deriving the optimal structure of the linear transceivers for both games, we
provided a unified set of sufficient conditions that guarantee the uniqueness
of the Nash equilibrium. In this Part II, we focus on the achievement of the
equilibrium and propose alternative distributed iterative algorithms that solve
both games. Specifically, the new proposed algorithms are the following: 1) the
sequential and simultaneous iterative waterfilling based algorithms,
incorporating spectral mask constraints; 2) the sequential and simultaneous
gradient projection based algorithms, establishing an interesting link with
variational inequality problems. Our main contribution is to provide sufficient
conditions for the global convergence of all the proposed algorithms which,
although derived under stronger constraints, incorporating for example spectral
mask constraints, have a broader validity than the convergence conditions known
in the current literature for the sequential iterative waterfilling algorithm.Comment: Paper submitted to IEEE Transactions on Signal Processing, February
22, 2006. Revised March 26, 2007. Accepted June 5, 2007. To appear on IEEE
Transactions on Signal Processing, 200
Linear programming on the Stiefel manifold
Linear programming on the Stiefel manifold (LPS) is studied for the first
time. It aims at minimizing a linear objective function over the set of all
-tuples of orthonormal vectors in satisfying additional
linear constraints. Despite the classical polynomial-time solvable case ,
general (LPS) is NP-hard. According to the Shapiro-Barvinok-Pataki theorem,
(LPS) admits an exact semidefinite programming (SDP) relaxation when
, which is tight when . Surprisingly, we can greatly
strengthen this sufficient exactness condition to , which covers the
classical case and . Regarding (LPS) as a smooth nonlinear
programming problem, we reveal a nice property that under the linear
independence constraint qualification, the standard first- and second-order
{\it local} necessary optimality conditions are sufficient for {\it global}
optimality when
Inexactness of SDP Relaxation and Valid Inequalities for Optimal Power Flow
It has been recently proven that the semidefinite programming (SDP)
relaxation of the optimal power flow problem over radial networks is exact
under technical conditions such as not including generation lower bounds or
allowing load over-satisfaction. In this paper, we investigate the situation
where generation lower bounds are present. We show that even for a two-bus
one-generator system, the SDP relaxation can have all possible approximation
outcomes, that is (1) SDP relaxation may be exact or (2) SDP relaxation may be
inexact or (3) SDP relaxation may be feasible while the OPF instance may be
infeasible. We provide a complete characterization of when these three
approximation outcomes occur and an analytical expression of the resulting
optimality gap for this two-bus system. In order to facilitate further
research, we design a library of instances over radial networks in which the
SDP relaxation has positive optimality gap. Finally, we propose valid
inequalities and variable bound tightening techniques that significantly
improve the computational performance of a global optimization solver. Our work
demonstrates the need of developing efficient global optimization methods for
the solution of OPF even in the simple but fundamental case of radial networks
Nondifferentiable multiobjective programming problem under strongly K-Gf-pseudoinvexity assumptions
[EN] In this paper we consider the introduction of the concept of (strongly) K-G(f)-pseudoinvex functions which enable to study a pair of nondifferentiable K-G- Mond-Weir type symmetric multiobjective programming model under such assumptions.Dubey, R.; Mishra, LN.; Sánchez Ruiz, LM.; Sarwe, DU. (2020). Nondifferentiable multiobjective programming problem under strongly
K-Gf-pseudoinvexity assumptions. Mathematics. 8(5):1-11. https://doi.org/10.3390/math8050738S11185Antczak, T. (2007). New optimality conditions and duality results of type in differentiable mathematical programming. Nonlinear Analysis: Theory, Methods & Applications, 66(7), 1617-1632. doi:10.1016/j.na.2006.02.013Antczak, T. (2008). On G-invex multiobjective programming. Part I. Optimality. Journal of Global Optimization, 43(1), 97-109. doi:10.1007/s10898-008-9299-5Ferrara, M., & Viorica-Stefanescu, M. (2008). Optimality conditions and duality in multiobjective programming with invexity. YUJOR, 18(2), 153-165. doi:10.2298/yjor0802153fChen, X. (2004). Higher-order symmetric duality in nondifferentiable multiobjective programming problems. Journal of Mathematical Analysis and Applications, 290(2), 423-435. doi:10.1016/j.jmaa.2003.10.004Long, X. (2013). Sufficiency and duality for nonsmooth multiobjective programming problems involving generalized univex functions. Journal of Systems Science and Complexity, 26(6), 1002-1018. doi:10.1007/s11424-013-1089-6Dubey, R., Mishra, L. N., & Sánchez Ruiz, L. M. (2019). Nondifferentiable G-Mond–Weir Type Multiobjective Symmetric Fractional Problem and Their Duality Theorems under Generalized Assumptions. Symmetry, 11(11), 1348. doi:10.3390/sym11111348Pitea, A., & Postolache, M. (2011). Duality theorems for a new class of multitime multiobjective variational problems. Journal of Global Optimization, 54(1), 47-58. doi:10.1007/s10898-011-9740-zPitea, A., & Antczak, T. (2014). Proper efficiency and duality for a new class of nonconvex multitime multiobjective variational problems. Journal of Inequalities and Applications, 2014(1). doi:10.1186/1029-242x-2014-333Dubey, R., Deepmala, & Narayan Mishra, V. (2020). Higher-order symmetric duality in nondifferentiable multiobjective fractional programming problem over cone contraints. Statistics, Optimization & Information Computing, 8(1), 187-205. doi:10.19139/soic-2310-5070-60
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