On the continuous side, research on the well-known Bundle methods for NonDifferentiable Optimization has lead to the assesment of theoretical results [CFN95,Fr97,Fr98,Fr02], as well as some practical codes that have significally improved performances w.r.t. the more commonly used subgradient algorithms. A black box has been developed and used for optimization of polyhedral functions arising as Lagrangean duals of large-scale (integer) linear problems. The code have shown to be efficient for lower bounds computation in [MP95], and for solution of (Fixed Charge) Multicommodity Min Cost Flow Problems [Fr97,CFG98,CFG00], both in sequential [FG99] and in parallel [CF02]. The use of this code within Branch And Bound algorithms have been throughly investigated [CF00]. As a part of this research, an efficient code for singly-constrained quadratic problems arising as search direction subproblems within Bundle algorithms has been developed and tested [Fr96].
On an entirely different subject, some results have been obtained on the well-known Bilevel Linear(/Quadratic) Problems [Fr95], class of difficult two-stage linear programs that are commonly used to model situations in which not all the optimization variables are controlled by the same decisor.
[CF02] P. Cappanera, A. Frangioni "Symmetric and Asymmetric Parallelization of a Cost-Decomposition Algorithm for Multi-Commodity Flow Problems" INFORMS JOC, to appear, 2002
[Fr02] A. Frangioni "Generalized Bundle Methods" SIAM J. on Opt., to appear, 2002
[CF00] P. Cappanera, A. Frangioni "Embedding a Bundle Method in a Branch and Bound Framework: an Application-Oriented Development" TR 09/00, Dip. di Informatica, Univ. di Pisa, 2000
[CFG00] T.G. Crainic, A. Frangioni and B. Gendron "Bundle-based Relaxation Methods for Multicommodity Capacitated Fixed Charge Network Design Problems" Discrete Applied Mathematics, to appear, 2000 (previously appeared as Publication CRT-98-45, Centre de Recherche sur les Transports, Université de Montreal)
[FG99] A. Frangioni, G. Gallo "A Bundle Type Dual-Ascent Approach to Linear Multicommodity Min Cost Flow Problems" INFORMS JOC 11(4), p. 370 - 393, 1999 (previously appeared as Techinical Report 01-96, Dipartimento di Informatica, Università di Pisa)
[CFG98] T.G. Crainic, A. Frangioni and B. Gendron "Multicommodity Capacitated Network Design", Chapter 1 in Telecommunications Network Planning, Soriano P. and Sanso B. editors, Kluwer Academics Publisher, p. 1 - 19, 1998 (previously appeared as Publication CRT-98-14, Centre de Recherche sur les Transports, Université de Montreal)
[Fr98] A. Frangioni "Generalized Bundle Methods" TR 04/98, Dip. di Informatica, Univ. di Pisa, 1998
[Fr97] A. Frangioni "Dual Ascent Methods and Multicommodity Flow Problems" Ph.D. Dissertation TD 5/97, Dip. di Informatica, Univ. di Pisa, 1997
[CFN96] P. Carraresi, A. Frangioni and M. Nonato "Applying Bundle Methods to Optimization of Polyhedral Functions: An Applications-Oriented Development" Ricerca Operativa, XXV, n.74, p. 5 - 49, 1996
[Fr96] A. Frangioni "Solving Semidefinite Quadratic Problems Within Nonsmooth Optimization Algorithms" Computers & OR 23(11), p. 1099 - 1118, 1996
[CFM95] P. Carraresi, F. Farinaccio and F. Malucelli "Testing epsilon-optimality for quadratic 0-1 unconstrained problems" TR 11/95, Dip. di Informatica, Univ. di Pisa, 1995 (to appear on Math. Prog.)
[Fr95] A. Frangioni "On a New Class of Bilevel Programming Problems and its Use For Reformulating Mixed Integer Problems" EJOR 82, p. 615-646, 1995
[M95] F. Malucelli "A polynomially solvable class of quadratic semi-assignment problems", 1995 (to appear on EJOR)
[MP95] F. Malucelli and D. Pretolani "Lower bounds for the Quadratic Semiassignment Problem", 1995 (to appear on EJOR)
[CM93] P. Carraresi and F. Malucelli "A reformulation scheme and new lower bounds for the quadratic assignment problem", To appear on Quadratic Assignment and Related Topics, ed. by P.M.Pardalos and H.Wolkowicz.
[CMP93] P. Carraresi, F. Malucelli and M. Pappalardo "Testing optimality for quadratic 0-1 unconstrained problems", TR 2/93, Dip. di Informatica, Univ. di Pisa, 1993 (to appear on Mathematical Methods of Operation Research)