Envy, Regret, and Social Welfare Loss

Incentive compatibility (IC) is a desirable property for any auction mechanism, including those used in online advertising. However, in real world applications practical constraints and complex environments often result in mechanisms that lack incentive compatibility. Recently, several papers investigated the problem of deploying black-box statistical tests to determine if an auction mechanism is incentive compatible by using the notion of IC-Regret that measures the regret of a truthful bidder. Unfortunately, most of those methods are computationally intensive, since they require the execution of many counterfactual experiments. In this work, we show that similar results can be obtained using the notion of IC-Envy. The advantage of IC-Envy is its efficiency: it can be computed using only the auction's outcome. In particular, we focus on position auctions. For position auctions, we show that for a large class of pricing schemes (which includes e.g. VCG and GSP), IC-Envy ≥ IC-Regret (and IC-Envy = IC-Regret under mild supplementary conditions). Our theoretical results are completed showing that, in the position auction environment, IC-Envy can be used to bound the loss in social welfare due to the advertiser untruthful behavior. Finally, we show experimentally that IC-Envy can be used as a feature to predict IC-Regret in settings not covered by the theoretical results. In particular, using IC-Envy yields better results than training models using only price and value features

Investigation of the active Celano-L'Aquila fault system, Abruzzi (central Apennines, Italy) with combined ground-penetrating radar and palaeoseismic trenching

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The asymptotic price of anarchy for k-uniform congestion games

We consider the atomic version of congestion games with affine cost functions, and analyze the quality of worst case Nash equilibria when the strategy spaces of the players are the set of bases of a k-uniform matroid. In this setting, for some parameter k, each player is to choose k out of a finite set of resources, and the cost of a player for choosing a resource depends affine linearly on the number of players choosing the same resource. Earlier work shows that the price of anarchy for this class of games is larger than 1.34 but at most 2.15. We determine a tight bound on the asymptotic price of anarchy equal to ≈1.35188. Here, asymptotic refers to the fact that the bound holds for all instances with sufficiently many players. In particular, the asymptotic price of anarchy is bounded away from 4/3. Our analysis also yields an upper bound on the price of anarchy <1.4131, for all instances

A photographic dataset of the coseismic geological effects induced on the environment by the 2012 Emilia (Northern Italy) earthquake sequence

We present a collection of pictures of the coseismic secondary geological effects produced on the environment by the 2012 Emilia seismic sequence in northern Italy. The May-June 2012 sequence struck a broad area located in the Po Plain region, causing 26 deaths and hundreds of injured, 15.000 homeless, severe damage of historical centres and industrial areas, and an estimated economic toll of ~2 billion of euros. The sequence included two mainshocks (Figure 1): the first one, with ML 5.9, occurred on May 20 between Finale Emilia, S. Felice sul Panaro and S. Martino Spino; the second one, with ML 5.8, occurred 12 km southwest of the previous mainshock on May 29. Both the mainshocks occurred on about E-W trending, S dipping blind thrust faults; the whole aftershocks area extends in an E-W direction for more than 50 km and includes five ML≥5.0 events and more than 1800 ML>1.5 events. Ground cracks and liquefactions were certainly the most relevant coseismic geological effects observed during the Emilia sequence. In particular, extensive liquefaction was observed over an area of ~1200 km2 following the May 20 and May 29 events. We collected all the coseismic geological evidence through field survey, helicopter and powered hang-glider trike survey, and reports from local people directly checked in the field. On the basis of their morphologic and structural characteristics the 1362 effects surveyed were grouped into three main categories: a) liquefactions related to overpressure of aquifers, occurring through several aligned vents forming coalescent flat cones (485 effects); b) liquefactions with huge amounts of liquefied sand and fine sand ejected from fractures tens of meters long (768); c) extensional fractures with small vertical throws, apparently organized in an en-echelon pattern, with no effects of liquefaction (109). The photographic dataset consists of 99 pictures of coseismic geological effects observed in 17 localities concentrated in the epicentral area. The pictures are sorted and presented by locality of observation; each photo reports several information such as the name of the site, the geographical coordinates and the type of effect observed. Figure 1 shows a map of the pictures sites along with the location of the two mainshocks; Figure 2 shows a detail of the distribution of the liquefactions in the area of S. Carlo. The complete description of the coseismic geological effects induced by the Emilia sequence, their relation with the aftershock area, the InSAR deformation area and the I>6 EMS felt area, along with the description of the technologies used for data sourcing and processing are shown in Emergeo Working Group [2012a and 2012b].Published1-703.2. Tettonica attivaN/A or not JCRope

Technologies and new approaches used by the INGV EMERGEO Working Group for real-time data sourcing and processing during the Emilia Romagna (northern Italy) 2012 earthquake sequence

No abstrac

Rilievi geologici nell’area epicentrale della sequenza sismica dell’Aquilano del 6 aprile 2009

Il 6 Aprile 2009 un terremoto di Ml=5.8 (Mw=6.2) ha colpito L’Aquila e la media valle dell’Aterno in Abruzzo. In questo lavoro presentiamo in maniera sintetica i rilievi geologici effettuati in campagna dal gruppo di lavoro EmerGeo a seguito della sequenza sismica aquilana. Le attività di rilevamento condotte sono consistite principalmente nella verifica, definizione e caratterizzazione delle deformazioni cosismiche superficiali osservate lungo le strutture tettoniche note in letteratura; sono stati inoltre rilevati e riportati altri effetti cosismici locali (fratture su asfalto, frane e scivolamenti) non direttamente collegati alla presenza di strutture tettoniche. In totale sono stati rilevati oltre 300 punti di osservazione su una porzione di territorio estesa circa 900 km2. L’analisi preliminare dei rilievi effettuati indica che le rotture osservate lungo la faglia di Paganica, per la continuità e le caratteristiche, rappresentano l’espressione superficiale della faglia responsabile dell’evento del 6 aprile 2009, e che le rotture lungo le faglie di Bazzano e di Monticchio-Fossa possono rappresentare l’espressione in superficie di una struttura antitetica riattivata durante l’evento

Investigation of the active Celano–L’Aquila fault system, Abruzzi

We studied fault scarps along the northern sector of the Celano–L’Aquila fault system in the Abruzzi region (central Apennines). Up to ∼9.5 km long, 3 m high, fault scarp traces mark the slope foot of ridgetop valleys at Mt Ocre range. In order to provide direct evidence of the deformation history of these scarps, we initiated geomorphic, ground-penetrating radar (GPR)and trenching investigations. GPR investigations yielded subsurface stratigraphic features of the scarp zones, and determined the locations for trenching sites. A total of five trenches were excavated at two different sites. Structural and stratigraphic analysis of the trench exposures combined with historical considerations, showed three faulting events between 5620 BC and 1300 AD; the most recent of them occurred after 1690 BC. Each of these events produced an estimated minimum vertical displacement ranging between 0.3 and 0.5 m. Our interpretation is that the Mt Ocre fault branch represents the northernmost surface expression of a single 35 km long seismogenic structure associated with M ∼7 earthquakes. Any attempt to estimate the seismic hazard in the area must consider the presence of this important source.Published805–8183.2. Tettonica attivaJCR Journalreserve