The main aim of this thesis is to investigate some problems relevant in enumeration and optimization, for which I present new theoretical results. First, I focus on a classical enumeration problem in graph theory with several applications, such as network reliability. Given an undirected graph, the objective is to list all its bonds, i.e., its minimal cuts. I provide two new algorithms, the former having the same time complexity as the state of the art by [Tsukiyama et al., 1980], whereas the latter offers an improvement. Indeed, by refining the branching strategy of [Tsukiyama et al., 1980] and relying on some dynamic data structures by [Holm et al., 2001], it is possible to define an eO(n)-delay algorithm to output each bond of the graph as a bipartition of the n vertices. Disregarding the polylogarithmic factors hidden in the eO notation, this is the first algorithm to list bonds in a time linear in the number of vertices. Then, I move to studying two well-known problems in theoretical computer science, that are checking the duality of two monotone Boolean functions, and computing the dual of a monotone Boolean function. Also these are relevant in many fields, such as linear programming. [Fredman and Khachiyan, 1996] developed the first quasi-polynomial time algorithm to solve the decision problem, thus proving that it is not coNP-complete. However, no polynomial-time algorithm has been discovered yet. Here, by focusing on the symmetry of the two input objects and exploiting full covers introduced by [Boros and Makino, 2009], I define an alternative decomposition approach. This offers a strong bound which, however, in the worst case, is still the same as [Fredman and Khachiyan, 1996]. Anyway, I also show how to adapt it to obtain a polynomial-space algorithm to solve the dualization problem. Finally, as extra content, this thesis contains an appendix about the topic of communicating operations research. By starting from two side projects not related to enumeration, and by comparing some relevant considerations and opinions by researchers and practitioners, I discuss the problem of properly promoting, fostering, and communicating findings in this research area to laypeople.

From optimization to listing: theoretical advances in some enumeration problems / Raffaele, Alice. - (2022 Mar 30), pp. 1-130. [10.15168/11572_335620]

### From optimization to listing: theoretical advances in some enumeration problems

#### Abstract

The main aim of this thesis is to investigate some problems relevant in enumeration and optimization, for which I present new theoretical results. First, I focus on a classical enumeration problem in graph theory with several applications, such as network reliability. Given an undirected graph, the objective is to list all its bonds, i.e., its minimal cuts. I provide two new algorithms, the former having the same time complexity as the state of the art by [Tsukiyama et al., 1980], whereas the latter offers an improvement. Indeed, by refining the branching strategy of [Tsukiyama et al., 1980] and relying on some dynamic data structures by [Holm et al., 2001], it is possible to define an eO(n)-delay algorithm to output each bond of the graph as a bipartition of the n vertices. Disregarding the polylogarithmic factors hidden in the eO notation, this is the first algorithm to list bonds in a time linear in the number of vertices. Then, I move to studying two well-known problems in theoretical computer science, that are checking the duality of two monotone Boolean functions, and computing the dual of a monotone Boolean function. Also these are relevant in many fields, such as linear programming. [Fredman and Khachiyan, 1996] developed the first quasi-polynomial time algorithm to solve the decision problem, thus proving that it is not coNP-complete. However, no polynomial-time algorithm has been discovered yet. Here, by focusing on the symmetry of the two input objects and exploiting full covers introduced by [Boros and Makino, 2009], I define an alternative decomposition approach. This offers a strong bound which, however, in the worst case, is still the same as [Fredman and Khachiyan, 1996]. Anyway, I also show how to adapt it to obtain a polynomial-space algorithm to solve the dualization problem. Finally, as extra content, this thesis contains an appendix about the topic of communicating operations research. By starting from two side projects not related to enumeration, and by comparing some relevant considerations and opinions by researchers and practitioners, I discuss the problem of properly promoting, fostering, and communicating findings in this research area to laypeople.
##### Scheda breve Scheda completa Scheda completa (DC)
30-mar-2022
XXXIII
2019-2020
Matematica (29/10/12-)
Mathematics
Rizzi, Romeo
no
Inglese
Settore MAT/09 - Ricerca Operativa
File in questo prodotto:
File
RaffaeleAlice-PhDThesis.pdf

accesso aperto

Descrizione: Testo integrale
Tipologia: Tesi di dottorato (Doctoral Thesis)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 3.43 MB
Formato Adobe PDF

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione

Utilizza questo identificativo per citare o creare un link a questo documento: `https://hdl.handle.net/11572/335620`
• ND
• ND
• ND