Verifying Safety Properties With the TLA+ Proof System

TLAPS, the TLA+ proof system, is a platform for the development and mechanical verification of TLA+ proofs written in a declarative style requiring little background beyond elementary mathematics. The language supports hierarchical and non-linear proof construction and verification, and it is independent of any verification tool or strategy. A Proof Manager uses backend verifiers such as theorem provers, proof assistants, SMT solvers, and decision procedures to check TLA+ proofs. This paper documents the first public release of TLAPS, distributed with a BSD-like license. It handles almost all the non-temporal part of TLA+ as well as the temporal reasoning needed to prove standard safety properties, in particular invariance and step simulation, but not liveness properties

Interactive comment on ″Comment on : ″Possible source of ancient carbon in phytolith concentrates from harvested grasses″ by G.M. Santos et al. (2012)″ by L.A. Sullivan and J.F. Parr

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Automated Reasoning and Presentation Support for Formalizing Mathematics in Mizar

This paper presents a combination of several automated reasoning and proof presentation tools with the Mizar system for formalization of mathematics. The combination forms an online service called MizAR, similar to the SystemOnTPTP service for first-order automated reasoning. The main differences to SystemOnTPTP are the use of the Mizar language that is oriented towards human mathematicians (rather than the pure first-order logic used in SystemOnTPTP), and setting the service in the context of the large Mizar Mathematical Library of previous theorems,definitions, and proofs (rather than the isolated problems that are solved in SystemOnTPTP). These differences poses new challenges and new opportunities for automated reasoning and for proof presentation tools. This paper describes the overall structure of MizAR, and presents the automated reasoning systems and proof presentation tools that are combined to make MizAR a useful mathematical service.Comment: To appear in 10th International Conference on. Artificial Intelligence and Symbolic Computation AISC 201

Aperture, A Large Telescope Using Magnetostriction For Post Deployment Corrections: Final Technical Report of NASA Innovative Advanced Concepts (NIAC) Phase I

In summary, astronomical as well as Earth observing applications of the future are counting on larger aperture telescopes than are currently available. Several groups have been working on the topic of enabling large (about 16-m diameter) UV-Vis telescopes for many years. The unique feature of our concept is that magnetic films are used rather than electrostatic films or piezo-electrostatic pads. Our magnetic film concept allows for contiguous correction along the surface, does not require a hard wire connection, and does not require continuous external application of the field. There are many unknowns related to the initial accuracy of the deployed figure prior to the magnetic write head corrections. The length scale over which the corrections need to be applied is also of concern. For, although approximately mm length scale corrections can be made with the MSM plus write head technology, the number of 1 mm patches in a 16 m diameter mirror is too large to contemplate applying individual corrections to each individual patch. However, deployment strategies and the materials available continue to evolve, in particular shape memory composites (SMCs) [34] or alloys (SMAs) [41], such that at this time we see no show-stoppers for this concept. Furthermore, the ability to tune deformations down to much (factors of 10-100) smaller (m) scale opens the futuristic possibility of improving the figure well beyond Strehl values of 90%

Divergent Biochemical Fractionation, Not Convergent Temperature, Explains Cellulose Oxygen Isotope Enrichment across Latitudes

Recent findings based on the oxygen isotope ratios of tree trunk cellulose indicate that the temperature of biomass production in biomes ranging from boreal to subtropical forests converge to an average leaf temperature of 21.4°C. The above conclusion has been drawn under the assumption that biochemically related isotopic fractionations during cellulose synthesis are not affected by temperature. Here we test the above assumption by heterotrophically generating cellulose at different temperatures and measuring the proportion of carbohydrate oxygen that exchange with water during cellulose synthesis and the average biochemical fractionation associated with this exchange. We observed no variation in the proportion of oxygen that exchange with different temperatures, which averaged 0.42 as it has been observed in other studies. On the other hand, the biochemical oxygen isotope fractionation during cellulose synthesis is affected by temperature and can be described by a 2nd order polynomial equation. The biochemical fractionation changes little between temperatures of 20 and 30°C averaging 26‰ but increases at lower temperatures to values of 31‰. This temperature sensitive biochemical fractionation explains the pattern of cellulose oxygen isotope ratios of aquatic plants encompassing several latitudes. The observed temperature sensitive biochemical fractionation also indicates that divergent biochemical fractionation and not convergent leaf temperature explains the increase in oxygen isotope enrichment of cellulose across several biomes

Effect of the pericarp on sugar beet (Beta vulgaris L.) seed germination : study of the energy metabolism

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