Between trees, webs and mirrors. Dimensions of Immanence and a critical post-structuralist proposal

L'articolo si propone di riprendere una analisi del rapporto fra il pensiero di Deleuze e gli sviluppi della semiotica e socio-semiotica

Semiotics, Deleuze (& Guattari) and post-structuralism. Further opening questions?

L'articolo cerca di riprendere ed approfondire il concetto di espressione nel pensiero di Deleuze (strettamente connesso con quello di immanenza, nella sua interpretazione spinozista) per confrontarlo con la categoria di epressione utilizzata in semiotica e in socio-smiotica; per vedere quali percorsi sia oggi possibile aprire o riaprire e percorrere soprattutto in rapporto con le altre scienze sociali

Forms of Economic DIscourse.

The aim of this paper is to propose a discussion concerning ANT approach, coming also from Latour and collaborators, and sociology of economy and of markets; and asking, finally, what is the effective contribute of socio-semiotic tools to this field of research

Actants, Actors, and Combat Units. The problem of conflict revisited: a semio-cultural viewpoint

The aim of this article is to discuss the question of conflict and war from a semio-cultural point of view. Starting from a tentative definition of war and conflict as the“borders” of a culture (even if in a paradoxical way), I shall discuss the specific links between war, conflict and narrative models. Secondly, the paper discusses diverse positions on the “polemogenic” mechanisms operating within cultures, along with their conflictual processes, such as the escalades. Starting from the work of Lotman, and intertwining his thought with concepts deriving from social systems theories, I shall discuss some hypothesis about “symmetry” and “asymmetry” inside cultures, and related questions concerning the growing of conflictual identities as perceived by the involved actors. This last point is tackled through case-studies from recent wars (such as civil and ethnic wars in former Yugoslavia) and the examination of their discursive devices

Language, culture, vision: some ideas for a critical approach

In questo articolo si cerca di fare il punto sulla ripresa recente dell'approccio culturalista e socio-culturalista nelle scienze cognitive e del linguaggio. Con la riscoperta e attualizzazione dell'ipotesi Sapir-Whorf nelle sue varianti e in rapporto alle altre scienze sociali e umane. In particolare come noto sono temi emergenti in questo ultimo decennio almeno quello dell'embodiment e dell'idea di "situatedness" nonch\ue9 di cognizione distribuita. Come questi concetti possono relazionarsi ad un approccio socio-semiotico? E socio-culturale

Mapping Cities: The Bologna Self-Mapping Project

IN questo saggio viene prima discusso il concetto di mappa, oggi e in confronto con le analisi urbane di tipo etnografico o socio-semiotico o, ancora, morfologico (come quelle pionieristiche di K. Lynch), E poi si presenta un progetto di "self-mapping" di mappatura della citt\ue0 di Bologna utilizzndo una metodologia di mappatura "dal basso" elaborata dall'autore assieme al gruppo di ricerca Unibo/Cube

Performance of a community detection algorithm based on semidefinite programming

The problem of detecting communities in a graph is maybe one the most studied inference problems, given its simplicity and widespread diffusion among several disciplines. A very common benchmark for this problem is the stochastic block model or planted partition problem, where a phase transition takes place in the detection of the planted partition by changing the signal-to-noise ratio. Optimal algorithms for the detection exist which are based on spectral methods, but we show these are extremely sensible to slight modification in the generative model. Recently Javanmard, Montanari and Ricci-Tersenghi [1] have used statistical physics arguments, and numerical simulations to show that finding communities in the stochastic block model via semidefinite programming is quasi optimal. Further, the resulting semidefinite relaxation can be solved efficiently, and is very robust with respect to changes in the generative model. In this paper we study in detail several practical aspects of this new algorithm based on semidefinite programming for the detection of the planted partition. The algorithm turns out to be very fast, allowing the solution of problems with O(105) variables in few second on a laptop computer

Phase Transitions in Semidefinite Relaxations

Statistical inference problems arising within signal processing, data mining, and machine learning naturally give rise to hard combinatorial optimization problems. These problems become intractable when the dimensionality of the data is large, as is often the case for modern datasets. A popular idea is to construct convex relaxations of these combinatorial problems, which can be solved efficiently for large scale datasets. Semidefinite programming (SDP) relaxations are among the most powerful methods in this family, and are surprisingly well-suited for a broad range of problems where data take the form of matrices or graphs. It has been observed several times that, when the `statistical noise' is small enough, SDP relaxations correctly detect the underlying combinatorial structures. In this paper we develop asymptotic predictions for several `detection thresholds,' as well as for the estimation error above these thresholds. We study some classical SDP relaxations for statistical problems motivated by graph synchronization and community detection in networks. We map these optimization problems to statistical mechanics models with vector spins, and use non-rigorous techniques from statistical mechanics to characterize the corresponding phase transitions. Our results clarify the effectiveness of SDP relaxations in solving high-dimensional statistical problems.Comment: 71 pages, 24 pdf figure