Provably Correct Floating-Point Implementation of a Point-In-Polygon Algorithm

The problem of determining whether or not a point lies inside a given polygon occurs in many applications. In air traffic management concepts, a correct solution to the point-in-polygon problem is critical to geofencing systems for Unmanned Aerial Vehicles and in weather avoidance applications. Many mathematical methods can be used to solve the point-in-polygon problem. Unfortunately, a straightforward floating- point implementation of these methods can lead to incorrect results due to round-off errors. In particular, these errors may cause the control flow of the program to diverge with respect to the ideal real-number algorithm. This divergence potentially results in an incorrect point-in- polygon determination even when the point is far from the edges of the polygon. This paper presents a provably correct implementation of a point-in-polygon method that is based on the computation of the winding number. This implementation is mechanically generated from a source- to-source transformation of the ideal real-number specification of the algorithm. The correctness of this implementation is formally verified within the Frama-C analyzer, where the proof obligations are discharged using the Prototype Verification System (PVS)

Independent Configurable Architecture for Reliable Operation of Unmanned Systems with Distributed Onboard Services

This paper presents the development of ICAROUS-2 (Independent Configurable Architecture for Reliable Operation of Unmanned Systems with Distributed Onboard Services), the second generation of a software architecture that integrates several algorithms as distributed onboard services to enable robust autonomous UAS applications. In particular, the ICAROUS architecture defines a framework to perform detect and avoid, geofencing, path monitoring, path planning, and autonomous decision making to ensure safety and mission progress. Most of the core algorithms implemented in ICAROUS are formally verified using an interactive theorem prover. These algorithms are composed together using a plan execution engine, whose operational semantics is formally specified. A description of the integrated architecture, services currently available, and flight test results highlighting the capability of ICAROUS are presented

A Mixed Real and Floating-Point Solver

Reasoning about mixed real and floating-point constraints is essential for developing accurate analysis tools for floating-point pro- grams. This paper presents FPRoCK, a prototype tool for solving mixed real and floating-point formulas. FPRoCK transforms a mixed formula into an equisatisfiable one over the reals. This formula is then solved using an off-the-shelf SMT solver. FPRoCK is also integrated with the PRECiSA static analyzer, which computes a sound estimation of the round-off error of a floating-point program. It is used to detect infeasible computational paths, thereby improving the accuracy of PRECiSA

A Learning-Based Guidance Selection Mechanism for a Formally Verified Sense and Avoid Algorithm

This paper describes a learning-based strategy for selecting conflict avoidance maneuvers for autonomous unmanned aircraft systems. The selected maneuvers are provided by a formally verified algorithm and they are guaranteed to solve any impending conflict under general assumptions about aircraft dynamics. The decision-making logic that selects the appropriate maneuvers is encoded in a stochastic policy encapsulated as a neural network. The networks parameters are optimized to maximize a reward function. The reward function penalizes loss of separation with other aircraft while rewarding resolutions that result in minimum excursions from the nominal flight plan. This paper provides a description of the technique and presents preliminary simulation results

An Abstract Interpretation Framework for the Round-Off Error Analysis of Floating-Point Programs

This paper presents an abstract interpretation framework for the round-off error analysis of floating-point programs. This framework defines a parametric abstract analysis that computes, for each combination of ideal and floating-point execution path of the program, a sound over-approximation of the accumulated floating-point round-off error that may occur. In addition, a Boolean expression that characterizes the input values leading to the computed error approximation is also computed. An abstraction on the control flow of the program is proposed to mitigate the explosion of the number of elements generated by the analysis. Additionally, a widening operator is defined to ensure the convergence of recursive functions and loops. An instantiation of this framework is implemented in the prototype tool PRECiSA that generates formal proof certificates stating the correctness of the computed round-off errors

Indium mediated isoprenylation of carbonyl compounds with 2-bromomethyl-1,3-butadiene: a short synthesis of (±)-ipsenol

Sentetz Blaise-Thérése. Décret sur des contestations entre le département et les districts du Gers, lors de la séance du 19 décembre 1790. In: Archives Parlementaires de 1787 à 1860 - Première série (1787-1799) Tome XXI - Du 26 novembre 1790 au 2 janvier 1791. Paris : Librairie Administrative P. Dupont, 1885. p. 563

Molecular Characterization Of A Family 5 Glycoside Hydrolase Suggests An Induced-fit Enzymatic Mechanism

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Glycoside hydrolases (GHs) play fundamental roles in the decomposition of lignocellulosic biomaterials. Here, we report the full-length structure of a cellulase from Bacillus licheniformis (BlCel5B), a member of the GH5 subfamily 4 that is entirely dependent on its two ancillary modules (Ig-like module and CBM46) for catalytic activity. Using X-ray crystallography, small-angle X-ray scattering and molecular dynamics simulations, we propose that the C-terminal CBM46 caps the distal N-terminal catalytic domain (CD) to establish a fully functional active site via a combination of large-scale multidomain conformational selection and induced-fit mechanisms. The Ig-like module is pivoting the packing and unpacking motions of CBM46 relative to CD in the assembly of the binding subsite. This is the first example of a multidomain GH relying on large amplitude motions of the CBM46 for assembly of the catalytically competent form of the enzyme.6Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2008/56255-9, 2009/52840-7, 2010/18773-8, 2013/08293-7, 2013/15582-5, 2014/10448-1]CNPq [490022/2009-0, 301981/2011-6, 500091/2014-5, 310177/2011-1]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Antocianinas em uvas de variedades viníferas

The occurrence of anthocyanins in varieties of red grapes, Bonarda, Merlot, Barbera D'Asti, Gamay-Beaujolais, Cabernet Franc, Pinot Noir and Canaiolo grown in Brazil, harvested in Bento Gonçalves, RS, Brazil, during the 1979's vintage, were studied. The separation was performed by thin-layer monodimensional chromatography. Results were expressed as malvidin-3-monoglucoside (mg/l). The varieties only presented anthocyanin-3-monoglucoside, which confirm its identification as Vitis vinifera. Knowledge of this may help in the detection of wine adulteration. "Pinot Noir" presented higher level in total anthocyanin, 764.12 mg/l, and Canaiolo, 501.49 mg/l, lower. A variation on anthocyanin concentrations among varieties was observed, indicating that it is possible to select varieties by the color intensity for red wine elaboration. Estudou-se, neste trabalho, na vindima de 1979, a ocorrência das antocianinas em variedades de uvas tintas, Bonarda, Merlot, Barbera D'asti, Gamay-Beaujolais, Cabernet Franc, Pinot Noir e Canaiolo, cultivadas na região vitivinícola de Bento Gonçalves, RS. A separação das antocianinas foi estudada por cromatografia em camada delgada unidimensional, e as concentrações, expressas em malvidina-3 monoglicosídeo (mg/l). As variedades estudadas somente apresentaram antocianinas-3-monoglicosídeos, comprovando, portanto, pertencerem à espécie Vitis vinifera. Essa identificação é de grande valia para a detecção de fraudes em vinhos finos tintos. A variedade "Pinot Noir" apresentou maior concentração, 764,12 mg/l; e a Canaiolo, 501,49 mg/l, a de menor concentração. Houve, contudo, uma variação entre as variedades estudadas, o que indica a possibilidade de seleção de variedades pela intensidade de cor, para a elaboração de vinhos tintos.