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

Stealing Sacraments: What Protestant Educators Can Learn from Other Religious Traditions

This somewhat provocative article is not a treatise on theological doctrine and interfaith dialogue, but addresses how adherents of various faith traditions practice their faith in ways that can enhance their witness in the world and from which Protestants should learn. The author calls these faith-building religious practices sacraments. He proposes that Protestant educators – whether in faith-based or in public schools which teach religion classes in their curriculum – would be wise to adapt the most effective means of nurturing faith in subscribers to other religious traditions; these means should be incorporated as a supplement to those practices most-commonly attempted in our instruction in religion or in other educational ministries. Examinations of three other-than-Protestant faith traditions – Mormon, Judaism, and Islam – are considered, and a case is made for a particular educational aspect of each to be rebaptized into the educational ministries of schools and/or churches

Events in Property Patterns

A pattern-based approach to the presentation, codification and reuse of property specifications for finite-state verification was proposed by Dwyer and his collegues. The patterns enable non-experts to read and write formal specifications for realistic systems and facilitate easy conversion of specifications between formalisms, such as LTL, CTL, QRE. In this paper, we extend the pattern system with events - changes of values of variables in the context of LTL.Comment: 14 pages, 3 figure

Consensus on Transaction Commit

The distributed transaction commit problem requires reaching agreement on whether a transaction is committed or aborted. The classic Two-Phase Commit protocol blocks if the coordinator fails. Fault-tolerant consensus algorithms also reach agreement, but do not block whenever any majority of the processes are working. Running a Paxos consensus algorithm on the commit/abort decision of each participant yields a transaction commit protocol that uses 2F +1 coordinators and makes progress if at least F +1 of them are working. In the fault-free case, this algorithm requires one extra message delay but has the same stable-storage write delay as Two-Phase Commit. The classic Two-Phase Commit algorithm is obtained as the special F = 0 case of the general Paxos Commit algorithm.Comment: Original at http://research.microsoft.com/research/pubs/view.aspx?tr_id=70

Advanced technical developments in support of scientific experiments in space

A technique was developed for preparing solid state, lithium-drifted silicon detectors. Hollow cylindrical detectors were built and tested for possible use as anticoincidence shields to replace conventional plastic scintillators and photomultipliers. A fission cell was developed for the Pioneer F/G instruments and the IMP I subsystem. An electron current detector was developed for Jovian belt measurements of electron flux. A number of circuits and semiconductor devices was also developed

On the Mailbox Problem

The Mailbox Problem was described and solved by Aguilera, Gafni, and Lamport in their 2010 DC paper with an algorithm that uses two flag registers that carry 14 values each. An interesting problem that they ask is whether there is a mailbox algorithm with smaller flag values. We give a positive answer by describing a mailbox algorithm with 6 and 4 values in the two flag registers

The cosmic ray telescope for the mariner-mars mission final engineering report

Cosmic ray telescope for Mariner space probe - test of component

The Emergent Use of Online Learning in Secondary Education: A Preliminary Review of the Literature

While the preponderance of online learning is geared toward adult learners, its use in the United States for secondary education students has been around for over a decade and has a growing literature. As online learning for adolescents gains popularity, questions are being raised about the quality, strategies, and effectiveness of the programs being offered. There are several delivery methods of online learning from the full-time virtual school to the ‘blended’ model. This review of the literature will provide an understanding of current theory and practice online learning for secondary students, recommendations for implementation, and where it may lead

Beneficial effects of dark chocolate for episodic memory in healthy young adults: a parallel-groups acute intervention with a white chocolate control

There is good evidence that cocoa flavonoids can acutely improve cognitive function in humans, possibly via mechanisms such as increased cerebral blood flow. To date, much of the evidence is based on measures of executive function with extracts and cocoa-based interventions with a high flavonoid content. The aim of the present study was to explore whether benefits to episodic verbal memory and mood are observed two hours post consumption of a commercially available dark chocolate (DC) bar relative to a 35 g white chocolate bar (WC). Ninety-eight healthy young adults (n = 57 females) aged 18−24 years consumed either a 35 g DC bar or a calorie-matched low flavonoid WC bar. Verbal episodic memory and mood were assessed pre consumption and 2 h post consumption. An ANOVA analysis showed that the DC was associated with better verbal memory performance for several outcome measures of the Rey Auditory Verbal Learning Test relative to the WC, however, there were no effects on mood. These findings lend support to the notion that everyday available portions of dark chocolate can confer benefits to the brain in healthy consumers

Do Metacognitive Strategies Improve Student Achievement in Secondary Science Classrooms?

Increasing prevalence of high-stakes testing calls for focus on value-added teaching and learning practices. Following is an inquiry regarding metacognitive teaching and learning practices as it pertains to secondary science classrooms. Research shows that the orchestration and inclusion of metacognitive strategies in the science classroom improve achievement under the following preconditions: (1) are pervasively embedded in the educational structure; (2) are part of appropriately rigorous and relevant curriculum; (3) are supported by ‘metacognitive friendly’ teaching strategies; (4) are explicitly practiced by students and teachers; and (5) enable students to take responsibility for their own learning