Australian stone buildings: nature, degradation and conservation

[EN] The contribution deals with stone buildings in Melbourne and Sydney built from the second half of the 19th century onwards. The results of a census of around 140 buildings are reported, analysed with respect to the type of stone used (sandstone, limestone, bluestone) and the degradation phenomena observed, in order to create the basis for establishing correlations between character and pathology. Taking into account the principles of the Burra Charter, which sets out cultural and operational criteria to be followed in restoration work, a number of significant sites were described, highlighting their operational methods and main conservation issues.[ES] La contribución trata sobre los edificios de piedra en Melbourne y Sydney construidos a partir de la segunda mitad del siglo XIX. Se reportan los resultados de un censo relativo a aproximadamente 140 edificios, analizados según el tipo de piedra utilizada (arenisca, caliza, piedra azul) y los fenómenos de degradación observados, con el fin de crear la base para definir relaciones entre carácter y patologías. Teniendo en cuenta los dictados de la Carta de Burra, que establece los criterios culturales y operativos a seguir en los trabajos de restauración, se han descrito algunas obras significativas, destacando los métodos operativos y los principales problemas de conservación.Trovò, F. (2022). Edificios de piedra australianos: naturaleza, degradación y conservación. Loggia, Arquitectura & Restauración. (35):40-59. https://doi.org/10.4995/loggia.2022.1712140593

Aspetti di continuità di lungo periodo dell'architettura di Venezia e osservazione sulla tipicità di alcuni processi di stratificazione

In order to interpret the links between Venice and Byzantium, it is firstly described how earliest houses in Venice were decorated by using sculptures coming from trading places. It is described the use of disassembled elements and the replacement of others, such as cornices, windows' elements, coats of arms, among others. These were used firstly as a revival (Neo-Byzantine, 15th century), and later as reflection of the Venetian society «prudence», related to its behaviours and traditions. This prudence is mainly shown in the Renaissance. Besides this, other aspects such as the type of building and the façades, which are the main transformed surface, are analysed with the aim of researching periodical and characteristic dynamics, mainly in those façades showing stylistic renewal and new elements. Some external façades have maintained specific and easy observable characteristics, so they can be associated to a determined stylistic and morphological period. Other façades are stratified, as it is shown by the presence of elements (windows, cornices, …) of different building phases. After tracing the main stratifying processes in about 40 study-cases, thanks to a macroscopic analysis, some ways of new composition elements and different stratified units are described. According to this, it is clear that the main principle is the searching for symmetry. Finally, some ways of intervention on the façades are described, highlighting some significant cases.[it] Nella prima parte dell'articolo viene descritto il modo di adornare le prime case veneziane con sculture importate dai luoghi del commercio, come ricostruzione del legame fra Venezia e Bisanzio. Si descrive l'uso di disaggregare e riposizionare vari elementi, come cornici, elementi di finestre, stemmi, prima come un iniziale revival, sia esso neobizantino o riferito al XV secolo, poi come manifestazione di «prudenza» della società veneziana, legata ai costumi, alle tradizioni. La principale manifestazione di tale prudenza è evidente nel periodo del rinascimento. Oltre alle tematiche maggiormente studiate come il concetto di tipo edilizio, anche le facciate, il luogo di maggior trasformazione, consentono la ricerca di dinamiche periodiche e caratterizzanti, soprattutto sui fronti che presentano aggiornamenti stilistici e una nuova composizione delle parti. Alcune facciate esterne hanno mantenuto una caratterizzazione specifica ben osservabile; in tal modo possono essere associate ad un preciso periodo stilistico-morfologico. Altre facciate sono stratificate, per la presenza di differenti fasi costruttive, leggibili attraverso diversi elementi (finestre, cornici…). Dopo l'illustrazione dei diversi processi di stratificazione su circa 40 casi studio, osservabili attraverso una lettura macroscopica, vengono descritte alcune modalità seguite nei processi di nuova composizione, leggibili a partire dal riconoscimento delle differenti unità stratigrafiche: risulta chiaro che il più importante principio è la ricerca di simmetria. Nell'ultima parte dell'articolo vengono descritti alcuni modi di intervento, sottolineando alcuni casi significativi

Unimodal Thompson Sampling for Graph-Structured Arms

We study, to the best of our knowledge, the first Bayesian algorithm for unimodal Multi-Armed Bandit (MAB) problems with graph structure. In this setting, each arm corresponds to a node of a graph and each edge provides a relationship, unknown to the learner, between two nodes in terms of expected reward. Furthermore, for any node of the graph there is a path leading to the unique node providing the maximum expected reward, along which the expected reward is monotonically increasing. Previous results on this setting describe the behavior of frequentist MAB algorithms. In our paper, we design a Thompson Sampling-based algorithm whose asymptotic pseudo-regret matches the lower bound for the considered setting. We show that -as it happens in a wide number of scenarios- Bayesian MAB algorithms dramatically outperform frequentist ones. In particular, we provide a thorough experimental evaluation of the performance of our and state-of-the-art algorithms as the properties of the graph vary

Truthful Learning Mechanisms for Multi-Slot Sponsored Search Auctions with Externalities

Sponsored search auctions constitute one of the most successful applications of microeconomic mechanisms. In mechanism design, auctions are usually designed to incentivize advertisers to bid their truthful valuations and to assure both the advertisers and the auctioneer a non-negative utility. Nonetheless, in sponsored search auctions, the click-through-rates (CTRs) of the advertisers are often unknown to the auctioneer and thus standard truthful mechanisms cannot be directly applied and must be paired with an effective learning algorithm for the estimation of the CTRs. This introduces the critical problem of designing a learning mechanism able to estimate the CTRs at the same time as implementing a truthful mechanism with a revenue loss as small as possible compared to an optimal mechanism designed with the true CTRs. Previous work showed that, when dominant-strategy truthfulness is adopted, in single-slot auctions the problem can be solved using suitable exploration-exploitation mechanisms able to achieve a per-step regret (over the auctioneer's revenue) of order $O(T^{-1/3})$ (where T is the number of times the auction is repeated). It is also known that, when truthfulness in expectation is adopted, a per-step regret (over the social welfare) of order $O(T^{-1/2})$ can be obtained. In this paper we extend the results known in the literature to the case of multi-slot auctions. In this case, a model of the user is needed to characterize how the advertisers' valuations change over the slots. We adopt the cascade model that is the most famous model in the literature for sponsored search auctions. We prove a number of novel upper bounds and lower bounds both on the auctioneer's revenue loss and social welfare w.r.t. to the VCG auction and we report numerical simulations investigating the accuracy of the bounds in predicting the dependency of the regret on the auction parameters

The role of craftsmanship in the conservation of Venice. State of the art and perspective

[EN] The case of Venice shows how the overall image, the perception of vernacularity of the historical built aggregates, strongly depends on the ability not only to preserve as much as possible, but also to "replicate" the consolidated building techniques to ensure continuity with the actions of restoration and consolidation. This option also contemplates forms of substitution and refurbishment, in contrast with the principles of conservation which favor the criterion of recognizability of the addition and reject the replacement of components, even when executed in an appropriate and harmonious manner, often the only option possible when attempting to preserve the Venetian character of the city’s buildings.The most pressing issue is that of the progressive disappearance of local craftsmanship. This is particularly dramatic in the case of Venice, where specific knowledge is needed in order to carry out interventions on elements of historical buildings. The objectives of protection are also of relevance in this case as they present particular difficulty for foreign workers or workers who have completed different training. In this regard, this text examines the measures implemented to counteract this phenomenon, particularly the effectiveness and role of each of the hypotheses examined, already partially addressed in the city, training courses for artisans and technicians; public subsidies and incentives and the role of the authorities.Trovò, F.; Vettore, E. (2022). The role of craftsmanship in the conservation of Venice. State of the art and perspective. Editorial Universitat Politècnica de València. 797-804. https://doi.org/10.4995/HERITAGE2022.2022.1569079780

Sobre la reciente tendencia de renovar las superficies exteriores de los edificios de Venecia

[EN] The text starts with a detailed description of the richness and subtlety of the traditional fi­nishing techniques used on Venetian façades and their evolution over the years and their cohabitation. It goes on to explain the protective urbanistic norms in force in Venice and how they have unwittingly brought about a general trend to renew the outer surfaces of buildings in Venice, eliminating historic traces and committing constructive mistakes, doing away with a great deal of the rich cultural historic fi­nishes that date back to Gothic or even Byzantine times. Finally, it examines the state of conservation of the surfaces renewed in recent years to underscore their scant durability and their fast, violent deterioration, as opposed to the slow, gradual degradation of the historic ­finishes.[ES] El texto parte de una descripción en detalle de la riqueza y sutileza de las técnicas de acabado tradicionales de las fachadas de Venecia y su evolución a lo largo del tiempo y convivencia entre las mismas. Acto seguido, expone la normativa urbanística de protección vigente en Venecia y cómo esta ha llegado a desencadenar a su pesar una tendencia generalizada a renovar las superficies exteriores de los edificios de Venecia, eliminando las trazas históricas y cometiendo incorrecciones gramaticales constructivas, dando al traste con gran parte de esta rica cultura material en acabados históricos que se remonta a época gótica o incluso bizantina. Por último, repasa el estado de conservación de las superficies renovadas en los últimos años, para incidir en su pobre durabilidad y en su forma violenta y abrupta de deteriorarse, frente a la degradación lenta y difuminada de los acabados históricos.Trovò, F.; Dato, PD. (2012). Sobre la reciente tendencia de renovar las superficies exteriores de los edificios de Venecia. Loggia, Arquitectura & Restauración. (24-25):44-57. doi:10.4995/loggia.2012.2997SWORD445724-2

Learning Probably Approximately Correct Maximin Strategies in Simulation-Based Games with Infinite Strategy Spaces

We tackle the problem of learning equilibria in simulation-based games. In such games, the players' utility functions cannot be described analytically, as they are given through a black-box simulator that can be queried to obtain noisy estimates of the utilities. This is the case in many real-world games in which a complete description of the elements involved is not available upfront, such as complex military settings and online auctions. In these situations, one usually needs to run costly simulation processes to get an accurate estimate of the game outcome. As a result, solving these games begets the challenge of designing learning algorithms that can find (approximate) equilibria with high confidence, using as few simulator queries as possible. Moreover, since running the simulator during the game is unfeasible, the algorithms must first perform a pure exploration learning phase and, then, use the (approximate) equilibrium learned this way to play the game. In this work, we focus on two-player zero-sum games with infinite strategy spaces. Drawing from the best arm identification literature, we design two algorithms with theoretical guarantees to learn maximin strategies in these games. The first one works in the fixed-confidence setting, guaranteeing the desired confidence level while minimizing the number of queries. Instead, the second algorithm fits the fixed-budget setting, maximizing the confidence without exceeding the given maximum number of queries. First, we formally prove {\delta}-PAC theoretical guarantees for our algorithms under some regularity assumptions, which are encoded by letting the utility functions be drawn from a Gaussian process. Then, we experimentally evaluate our techniques on a testbed made of randomly generated games and instances representing simple real-world security settings

RI-abitare l’oggi : intorno al progetto di riuso

Interi paesi fantasma, un patrimonio demaniale in disuso e in cerca di valorizzazione, caserme e carceri obsolete o abbandonate collocate all’interno dei centri urbani, capannoni industriali vuoti e un numero crescente di centri commerciali poco o per niente frequentati nelle aree di connessione tra città e campagna, interi complessi industriali abbandonati, palazzi pubblici e privati di dimensione, organizzazione e dotazione di servizi non adeguati alle esigenze odierne. E ancora, chiese, barchesse, scuole, ex colonie ma anche edifici residenziali del tessuto storico urbano e non, architetture storiche e monumentali dal grande valore culturale da rendere funzionali per i diversi usi attuali: sono diversi e sempre più evidenti gli esempi di un patrimonio da riconsiderare, in un’ottica di riutilizzo sostenibile del costruito inteso come risorsa da non sprecare, su cui convergono molteplici obiettivi europei, quali l’incremento dell’efficienza energetica legata al Green New Deal e il raggiungimento del traguardo di zero consumo di suolo, mediante un riuso selettivo e appropriato dell’esistente. In Italia, per la storia plurimillenaria e la forte tradizione identitaria caratterizzata dal ruolo significativo del costruito storico, in cui affondano le radici culturali del Paese, queste sfide richiedono lo sviluppo di un pensiero evoluto sul progetto, in cui l’innovazione e la continuità possano integrarsi, confrontandosi con i principi della Dichiarazione di Davos 2018 Verso una Baukultur di alta qualità per l’Europa e del New European Bauhaus. Sono questi i nuovi temi – o temi noti da riconsiderare – che l’architettura contemporanea deve affrontare, sollecitando una riflessione sui modi di intervenire sul patrimonio costruito e sul ruolo esercitato dalle diverse discipline