AMS Acta
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Repository of the University of Bologna.

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1.
Community-based Enterprises in Italy: Definition and Governance Models - Bandini, Federica; Renato, Medei; Claudio, Travaglini
In recent years, a new form of co-operative business is taking shape in Italy: the community-based enterprise, a community acting collectively at both management and business level, to pursue common goals. Community-based enterprises grow on a system of networks of free relationships among the members of a local community, with a high degree of reciprocity; when individuals work together in a business systems, relationships become social relationships. The complex of the community members’ relationships, objectives and expectations towards the company reflects necessarily on governance models that should follow a multistakeholder pattern. Multistakeholdership implies a direct and active participation of subjects...

2.
Reeb graphs of surfaces are stable under function perturbations - Di Fabio, Barbara; Landi, Claudia
Reeb graphs are combinatorial signatures that capture shape
properties from the perspective of a chosen function. One of the
most important questions is whether Reeb graphs are robust against
function perturbations that may occur because of noise and
approximation errors in the data acquisition process. In this work
we tackle the problem of stability providing an editing distance
between Reeb graphs of orientable surfaces in terms of the cost
necessary to transform one graph into another by edit operations.
Our main result is that changes in the functions, measured by the
maximum norm, imply not greater changes in this distance, yielding
the stability property under function perturbations.

3.
Social capital, institutions and policy making - Savioli, Marco
Economic processes, consisting of interactions between human beings, exploit the social capital of persons endowed with specific culture and identities. The role of institutions and policy makers is to build positive social capital and exploit it to reach their objectives. However, social capital is elusive and has several dimensions by which to interpret its multifaceted functions in economics and society. We cannot forget, furthermore, that social capital sometimes is undesirable for society, for instance when used for unethical uses. Even so, it is widely accepted that social capital has stable and positive effects.

4.
Both On and Under the Surface of Discourse: Tagged Corpora for
the Functional Description of Conjunctive Language - Cresswell, Andy
This paper reports an eight-stage procedure for tagging small specialised corpora with logical relations, grounded in the coding of two corpora of argumentative writing – one learner corpus, and one expert corpus. The tagset was developed out of Rhetorical Structure Theory. Tagging involved adjusting mark-up added by the RST Tool tree diagram program to produce a corpus with cocoa tags easily searchable with KWIC concordancing software. Results show disambiguation of form-function relationships in conjunction and a wide range of types of conjunctive language. Potential further applications in research and teaching are discussed.

5.
Italians in the ‘Old Shanghai’: a Preliminary Contribution - Piastra, Stefano
Besides other Western nationalities, ‘Old Shanghai’ also hosted an Italian community, which experienced, throughout the years, a slight development, particularly after the establishment there of the consulate of the Kingdom of Sardinia in 1860 (later kept by the new Kingdom of Italy), and the signing, in 1866, of a Sino-Italian Treaty (ratified in Shanghai in 1867). It was a small group, if compared with the English, the Americans or the French (from some dozens to some hundreds between the 19th and the 20th centuries), but it had distinctive spatial and socio-economic urban patterns: in ‘Old Shanghai’, there were specific areas...

8.
Filtrations induced by continuous functions - Di Fabio, Barbara; Frosini, Patrizio
In Persistent Homology and Topology, filtrations are usually given by introducing an ordered collection of sets or a continuous function from a topological space to $\R^n$. A natural question arises, whether these approaches are equivalent or not. In this paper we study this problem and prove that, while the answer to the previous question is negative in the general case, the approach by continuous functions is not restrictive with respect to the other, provided that some natural stability and completeness assumptions are made. In particular, we show that every compact and stable $1$-dimensional filtration of a compact
metric space is induced...

9.
G-invariant Persistent Homology - Frosini, Patrizio
Classical persistent homology is a powerful mathematical tool for shape comparison. Unfortunately, it is not tailored to study the action of transformation groups that are different from the group Homeo(X) of all self-homeomorphisms of a topological space X. This fact greatly restricts its use in applications. In order to obtain better lower bounds for the natural pseudo-distance d_G associated with a subgroup G of the group Homeo(X), we need to adapt persistent homology and consider G-invariant persistent homology. Roughly speaking, the main idea consists in defining persistent homology by means of a set of chains that is invariant under the...

10.
G-invariant Persistent Homology - Frosini, Patrizio
Classical persistent homology is not tailored to study the action of transformation groups different from the group Homeo(X) of all self-homeomorphisms of a topological space X. In order to obtain better lower bounds for the natural pseudo-distance d_G associated with a subgroup G of Homeo(X), we need to adapt persistent homology and consider G-invariant
persistent homology. Roughly speaking, the main idea consists in defining persistent homology by means of a set of chains that is invariant under the action of G. In this paper we formalize this idea, and prove the stability of G-invariant persistent homology with respect to the natural...

11.
G-invariant Persistent Homology - Frosini, Patrizio
Classical persistent homology is not tailored to study the action of transformation groups different from the group Homeo(X) of all self-homeomorphisms of a topological space X. In order to obtain better lower bounds for the natural pseudo-distance d_G associated with a subgroup G of Homeo(X), we need to adapt persistent homology and consider G-invariant
persistent homology. Roughly speaking, the main idea consists in defining persistent homology by means of a set of chains that is invariant under the action of G. In this paper we formalize this idea, and prove the stability of G-invariant persistent homology with respect to the natural...

12.
“Futurama II”. Tracking the ‘Presence of the Future’ in Contemporary Architecture Representations. - Maahsen-Milan, Andreina; Pellegrino, Margot
This text intends to discuss the profile of three architects belonging to the past century: Enzo Venturelli, Claude Parent and Roger Anger. The aim is to compare their representations to prefigure their ideal towns. Interest is even greater, if we hypothesize and sustain the existence of a link be-tween these three personalities which is far from being simply indirect. A new interpretation of the three authors highlights common cultural aspects. The identified links open up new prospects for investigation, substantiated by an exam of the works of these three architects. In particular, a spe-cific element is compared: the representation –...

13.
Economic and cultural factors and illegal copying in the university textbook market - Scorcu, Antonello Eugenio; Vici, Laura
The role of economic factors, such as family income, the price of illegal reproductions of books, the enforcement rules and the expected penalties are considered the main determinants of the possible infringements of the copyright law. However, the comparison between individual economic gains and losses offers only a partial explanation, as also cultural individual habits and peer effects exert important influences. Using a unique dataset based on a survey conducted at the University of Bologna, Italy, this paper analyses empirically the relevance of socio-economic as well as cultural determinants in the decision process of using illegal copies of university textbooks....

14.
Il distretto come modello intersettoriale di sviluppo del territorio - Mariotti, Alessia
Partendo dalla descrizione del distretto industriale come modello di interpretazione della complessità territoriale, il presente saggio vuole fornire qualche spunto di riflessione sulla valenza scientifica di tale approccio nella sua applicazione ad altri settori dell’economia, rispetto a quelli più propriamente produttivi. La lettura del territorio e più precisamente delle potenzialità di sfruttamento efficiente delle sue risorse al fine di favorirne lo sviluppo, può passare attraverso l’applicazione di alcuni degli aspetti fondamentali del distretto industriale ad aree di interesse che recentemente hanno visto aumentare la loro importanza relativa nelle scelte di politica economica: la cultura ed il turismo. Saranno posti quindi...

16.
Influenza delle dimensioni della densità e della concentrazione delle particelle sull'usura erosiva nel trasporto pneumatico - Bianchini, Augusto; Bradley, Mike; Deng, Tong; Macchini, Romeo
La concentrazione di particelle è uno dei fattori principali che influenzano la velocità di erosione delle superfici in caso di urto delle particelle, come accade per esempio nelle curve dei trasportatori pneumatici. È noto che una riduzione della velocità di erosione si verifica per alte concentrazioni di particelle, un fenomeno denominato "effetto schermo ". La causa della schermatura si crede risiedere nella maggiore probabilità di collisioni inter-particella quando la concentrazione aumenta. In questo studio sono stati indagati gli effetti della concentrazione sull’erosione di una superficie curva in acciaio utilizzando tre diversi materiali in un impianto di trasporto pneumatico. I materiali...

17.
The natural pseudo-distance as a quotient pseudo-metric, and applications - Cagliari, Francesca; Di Fabio, Barbara; Landi, Claudia
The natural pseudo-distance is a similarity measure conceived for the purpose of comparing shapes. In this paper we revisit this pseudo-distance from the point of view of quotients. In particular, we show that the natural pseudo-distance coincides with the quotient pseudo-metric on the space of continuous functions on a compact manifold, endowed with the uniform convergence metric, modulo self-homeomorphisms of the manifold. As applications of this result, the natural pseudo-distance is shown to be actually a metric on a number of function subspaces such as
the space of topological embeddings, of isometries, and of simple Morse functions on surfaces.

18.
Multi-scale approaches for the matching distance estimation - Cerri, Andrea; Di Fabio, Barbara; Jablonski, Grzegorz; Medri, Filippo
This paper deals with the concepts of persistence diagram and matching distance. These are two of the main ingredients of Topological Persistence, which has proven to be a promising framework for shape comparison. Persistence diagrams are descriptors providing a signature of the shapes under study, while the matching distance is a metric to compare them. One drawback in the application of these tools is the computational cost for the evaluation of the matching distance. The aim of the present paper is to introduce a new framework for the approximation of the
matching distance, which does not affect the reliability of the...

20.
Il contributo del teleriscaldamento al miglioramento energetico ed ambientale
Studio del caso nella provincia di Forlì - Golfera, Luca; Pellegrini , Marco; Bianchini, Augusto; Saccani, Cesare
Scopo primario di questo elaborato è comparare la scelta di adottare un impianto di teleriscaldamento centralizzato associato ad una pompa di calore in alternativa al tradizionale riscaldamento autonomo con caldaie a gas; evidenziando l’impatto economico ed ambientale di entrambe le soluzioni. Dopodiché si prosegue indicando la possibilità per il riscaldamento centralizzato di adottare una filtro innovativo ad impatto nullo, in grado di agire anche sull’aria ambiente come mezzo attivo per ridurre le PM10.