Incrementally Computing Minimal Unsatisfiable Cores of QBFs via a Clause Group Solver API

We consider the incremental computation of minimal unsatisfiable cores (MUCs) of QBFs. To this end, we equipped our incremental QBF solver DepQBF with a novel API to allow for incremental solving based on clause groups. A clause group is a set of clauses which is incrementally added to or removed from a previously solved QBF. Our implementation of the novel API is related to incremental SAT solving based on selector variables and assumptions. However, the API entirely hides selector variables and assumptions from the user, which facilitates the integration of DepQBF in other tools. We present implementation details and, for the first time, report on experiments related to the computation of MUCs of QBFs using DepQBF's novel clause group API.Comment: (fixed typo), camera-ready version, 6-page tool paper, to appear in proceedings of SAT 2015, LNCS, Springe

On Tackling the Limits of Resolution in SAT Solving

The practical success of Boolean Satisfiability (SAT) solvers stems from the CDCL (Conflict-Driven Clause Learning) approach to SAT solving. However, from a propositional proof complexity perspective, CDCL is no more powerful than the resolution proof system, for which many hard examples exist. This paper proposes a new problem transformation, which enables reducing the decision problem for formulas in conjunctive normal form (CNF) to the problem of solving maximum satisfiability over Horn formulas. Given the new transformation, the paper proves a polynomial bound on the number of MaxSAT resolution steps for pigeonhole formulas. This result is in clear contrast with earlier results on the length of proofs of MaxSAT resolution for pigeonhole formulas. The paper also establishes the same polynomial bound in the case of modern core-guided MaxSAT solvers. Experimental results, obtained on CNF formulas known to be hard for CDCL SAT solvers, show that these can be efficiently solved with modern MaxSAT solvers

Environmental Seismic Intensity scale - ESI 2007 La scala di Intensità Sismica basata sugli effetti ambientali - ESI 2007

ABSTRACT - The Environmental Seismic Intensity scale (ESI 2007) is2007) is a new earthquake intensity scale only based on the effects triggered by the earthquake in the natural environment. The coseismic effects considered more diagnostic for intensity evaluation are surface faulting and tectonic uplift/subsidence (primary effects), landslides, ground cracks, liquefactions, displaced boulders, tsunami and hydrological anomalies (secondary effects). The ESI 2007 scale follows the same basic structure as any other XII degree scale, such as the MCS, MM, MSK and EMS scales. This type of intensity scale was proposed to the scientific community since the beginning of '90s. The idea was definitely accepted in 1999, when a first version of the scale was developed by a Working Group of geologists, seismologists and engineers sponsored by the International Union for Quaternary Research (INQUA). In the following years, this version has been revised and updated. The ESI 2007 scale is the result of the revision of previous versions after its application to a large number of earthquakes worldwide. In the frame of INQUA SubCommission on Paleoseismicity, this activity was conducted by academic and research institutes coordinated by the Geological Survey of Italy - APAT (for further details, s e e h t t p : / / w w w. a p a t . g o v. i t / s i t e / e n - GB/Projects/INQUA_Scale/default.html). For intensity levels lower than IX, the main goal of this new scale is to bring the environmental effects in line with the damage indicators. In this range, the ESI 2007 scale should be used along with the other scales. In the range between X and XII, the distribution and size of environmental effects, specially primary tectonic features, becomes the most diagnostic tool to assess the intensity level. Documentary report and/or field observations on fault rupture length and surface displacement should be consistently implemented in the macroseismic study of past and future earthquakes. Therefore, the use of the ESI 2007 alone is recommended only when effects on humans and on manmade structures i) are absent, or too scarce (i.e. in sparsely populated or desert areas), and ii) saturate (i.e., for intensity X to XII) loosing their diagnostic value. After its official approval at the 17th INQUA Congress, the use of the ESI 2007 scale will be proposed to national institutions (geological surveys, academic and research institutes, departments for civil protection, environmental agencies, etc.), dealing in the field of earthquake intensity and seismic hazar

Genetic Relations Between the Aves Ridge and the Grenada Back-Arc Basin, East Caribbean Sea

The Grenada Basin separates the active Lesser Antilles Arc from the Aves Ridge, described as a Cretaceous‐Paleocene remnant of the “Great Arc of the Caribbean.” Although various tectonic models have been proposed for the opening of the Grenada Basin, the data on which they rely are insufficient to reach definitive conclusions. This study presents, a large set of deep‐penetrating multichannel seismic reflection data and dredge samples acquired during the GARANTI cruise in 2017. By combining them with published data including seismic reflection data, wide‐angle seismic data, well data and dredges, we refine the understanding of the basement structure, depositional history, tectonic deformation and vertical motions of the Grenada Basin and its margins as follows: (1) rifting occurred during the late Paleocene‐early Eocene in a NW‐SE direction and led to seafloor spreading during the middle Eocene; (2) this newly formed oceanic crust now extends across the eastern Grenada Basin between the latitude of Grenada and Martinique; (3) asymmetrical pre‐Miocene depocenters support the hypothesis that the southern Grenada Basin originally extended beneath the present‐day southern Lesser Antilles Arc and probably partly into the present‐day forearc before the late Oligocene‐Miocene rise of the Lesser Antilles Arc; and (4) the Aves Ridge has subsided along with the Grenada Basin since at least the middle Eocene, with a general subsidence slowdown or even an uplift during the late Oligocene, and a sharp acceleration on its southeastern flank during the late Miocene. Until this acceleration of subsidence, several bathymetric highs remained shallow enough to develop carbonate platforms

SUNNY-CP : a Sequential CP Portfolio Solver

International audienceThe Constraint Programming (CP) paradigm allows to model and solve Constraint Satisfaction / Optimization Problems (CSPs / COPs). A CP Portfolio Solver is a particular constraint solver that takes advantage of a portfolio of different CP solvers in order to solve a given problem by properly exploiting Algorithm Selection techniques. In this work we present sunny-cp: a CP portfolio for solving both CSPs and COPs that turned out to be competitive also in the MiniZinc Challenge, the reference competition for CP solvers

Development of an Agrobacterium transformation system for onion (Allium cepa L.)

Onion (Allium cepa) bulbs of the New Zealand-bred cultivars 'Pukekohe Longkeeper' and 'Early Longkeeper' produced tumourous growths after inoculation with 25 virulent strains of Agrobactenum tumefaciens, A. rubi and A. rhizogenes. The majority of these tumours produced nopaline, indicating that tumour cells were transformed. Some excised tumours produced roots in sterile culture. Eight onion genotypes were screened in tissue culture for callus formation, regeneration of plantlets from callus and clonal multiplication by shoot proliferation. All genotypes could be clonally multiplied and four were readily regenerable from callus. A technique for plantlet multiplication, which uses longitudinally-bisected stems of in vitro-germinated onion seedlings as explants, was developed. Onion (‘Pukekohe Longkeeper', 'Southport White Globe', 'Japanese Saporo Yellow' and 'Hikeeper Fl ') protoplasts were isolated and cultured on a range of media. These protoplasts formed new cell walls and sometimes divided, but only first divisions were regularly seen. Kanamycin, geneticin (G418), hygromycin and chlorsulfuron were evaluated for their use as selective agents in onion transformation experiments. Tissues surveyed for sensitivity to these selective agents included seeds and seedlings on germination and callusing media, established callus on callusing and regeneration media, and shoot cultures on shoot proliferation medium. Hygromycin was shown to be the antibiotic most toxic to tissues of all the surveyed onion cultivars, with effects being obvious in all tissues after 4-5 weeks of culture on concentrations as low as 20 mgl-1. Kanamycin was shown to be the least toxic of the selection agents surveyed. The kanamycin analogue G418 was considerably more toxic to most onion cultures than kanamycin. However, responses of cultures to G418 were slower than those to hygromycin. The herbicide chlorsulfuron was also shown to be toxic to onion seedlings and shoot cultures. The ability of Agrobacterium tumefaciens to transfer foreign genes to A. cepa was demonstrated. A single, putatively transformed plantlet (RC1), was regenerated from an onion seedling stem via callus, following co-cultivation of stem explants with Agrobacterium strain LBA4404 harbouring the binary vector pKIWI110. In addition, 41 auxiliary or adventitious shoots which grew directly from basal plates injected in vitro with four strains of A. tumefaciens (each harbouring the binary vectors pKIWI110 or pGA643) exhibited resistance to G418 in culture. The binary vectors used carry the neomycin phosphotransferase II gene (nptII) controlled by the nopaline synthase (nos) promoter. Both RC1 and some of the shoots growing from basal plate explants produced roots when grown on culture media supplemented with G418. Southern analyses showed that fragments of DNA from RC1 and from five of the 41 G418-resistant shoots hybridized to a 1.25 kbp nptII probe. (β- glucuronidase (GUS) activity was detected in over half of the plantlets derived from basal plate tissue injected with A. tumefaciens strains LBA4404 or C58, both of which harboured pKIWI110. Molecular and phenotypic evidence suggested that the putatively transformed plants produced from injected basal plate tissues were chimeric

Revealing hidden species distribution with pheromones: the case of Synanthedon vespiformis (Lepidoptera: Sesiidae) in Sweden

Synanthedon vespiformis L. (Lepidoptera: Sesiidae) is considered a rare insect in Sweden, discovered in 1860, with only a few observations recorded until a sex pheromone attractant became available recently. This study details a national survey conducted using pheromones as a sampling method for this species. Through pheromone trapping we captured 439 specimens in Southern Sweden at 77 sites, almost tripling the number of previously reported records for this species. The results suggest that S. vespiformis is truly a rare species with a genuinely scattered distribution, but can be locally abundant. Habitat analyses were conducted in order to test the relationship between habitat quality and the number of individuals caught. In Sweden, S. vespiformis is thought to be associated with oak hosts, but our attempts to predict its occurrence by the abundance of oaks yielded no significant relationships. We therefore suggest that sampling bias and limited knowledge on distribution may have led to the assumption that this species is primarily reliant on oaks in the northern part of its range, whereas it may in fact be polyphagous, similar to S. vespiformis found as an agricultural pest in Central and Southern Europe. We conclude that pheromones can massively enhance sampling potential for this and other rare lepidopteran species. Large-scale pheromone-based surveys provide a snapshot of true presences and absences across a considerable part of a species national distribution range, and thus for the first time provide a viable means of systematically assessing changes in distribution over time with high spatiotemporal resolution