10,932 research outputs found
Interactive Simplifier Tracing and Debugging in Isabelle
The Isabelle proof assistant comes equipped with a very powerful tactic for
term simplification. While tremendously useful, the results of simplifying a
term do not always match the user's expectation: sometimes, the resulting term
is not in the form the user expected, or the simplifier fails to apply a rule.
We describe a new, interactive tracing facility which offers insight into the
hierarchical structure of the simplification with user-defined filtering,
memoization and search. The new simplifier trace is integrated into the
Isabelle/jEdit Prover IDE.Comment: Conferences on Intelligent Computer Mathematics, 201
Isabelle/PIDE as Platform for Educational Tools
The Isabelle/PIDE platform addresses the question whether proof assistants of
the LCF family are suitable as technological basis for educational tools. The
traditionally strong logical foundations of systems like HOL, Coq, or Isabelle
have so far been counter-balanced by somewhat inaccessible interaction via the
TTY (or minor variations like the well-known Proof General / Emacs interface).
Thus the fundamental question of math education tools with fully-formal
background theories has often been answered negatively due to accidental
weaknesses of existing proof engines.
The idea of "PIDE" (which means "Prover IDE") is to integrate existing
provers like Isabelle into a larger environment, that facilitates access by
end-users and other tools. We use Scala to expose the proof engine in ML to the
JVM world, where many user-interfaces, editor frameworks, and educational tools
already exist. This shall ultimately lead to combined mathematical assistants,
where the logical engine is in the background, without obstructing the view on
applications of formal methods, formalized mathematics, and math education in
particular.Comment: In Proceedings THedu'11, arXiv:1202.453
THE EFFECTS OF THE MICRO-MARKET STRUCTURE ON ILLINOIS ELEVATOR SPATIAL CORN PRICE DIFFERENTIALS
Corn price differentials among Illinois elevators can often exceed transportation costs. Using primary data, we examine the effects of micro-market structure variables on the differentials in bids prices offered by Illinois elevators. Our findings suggest the existence of a highly developed, responsive market of competing firms, operating in an industry that can be characterized by monopsonistic competition, and to some extent by seasonally induced market power. Local supply conditions, firm productive efficiency, and their operating practices influence price differentials. Further, firm type, final market destination of the grain, and period of the marketing year affect price differentials.Market structure, Corn price differentials, Marketing,
Human Neutrophil Elastase Degrades SPLUNC1 and Impairs Airway Epithelial Defense against Bacteria
Background:Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) are a significant cause of mortality of COPD patients, and pose a huge burden on healthcare. One of the major causes of AECOPD is airway bacterial (e.g. nontypeable Haemophilus influenzae [NTHi]) infection. However, the mechanisms underlying bacterial infections during AECOPD remain poorly understood. As neutrophilic inflammation including increased release of human neutrophil elastase (HNE) is a salient feature of AECOPD, we hypothesized that HNE impairs airway epithelial defense against NTHi by degrading airway epithelial host defense proteins such as short palate, lung, and nasal epithelium clone 1 (SPLUNC1).Methodology/Main Results:Recombinant human SPLUNC1 protein was incubated with HNE to confirm SPLUNC1 degradation by HNE. To determine if HNE-mediated impairment of host defense against NTHi was SPLUNC1-dependent, SPLUNC1 protein was added to HNE-treated primary normal human airway epithelial cells. The in vivo function of SPLUNC1 in NTHi defense was investigated by infecting SPLUNC1 knockout and wild-type mice intranasally with NTHi. We found that: (1) HNE directly increased NTHi load in human airway epithelial cells; (2) HNE degraded human SPLUNC1 protein; (3) Recombinant SPLUNC1 protein reduced NTHi levels in HNE-treated human airway epithelial cells; (4) NTHi levels in lungs of SPLUNC1 knockout mice were increased compared to wild-type mice; and (5) SPLUNC1 was reduced in lungs of COPD patients.Conclusions:Our findings suggest that SPLUNC1 degradation by neutrophil elastase may increase airway susceptibility to bacterial infections. SPLUNC1 therapy likely attenuates bacterial infections during AECOPD. © 2013 Jiang et al
Capturing Hiproofs in HOL Light
Hierarchical proof trees (hiproofs for short) add structure to ordinary proof
trees, by allowing portions of trees to be hierarchically nested. The
additional structure can be used to abstract away from details, or to label
particular portions to explain their purpose. In this paper we present two
complementary methods for capturing hiproofs in HOL Light, along with a tool to
produce web-based visualisations. The first method uses tactic recording, by
modifying tactics to record their arguments and construct a hierarchical tree;
this allows a tactic proof script to be modified. The second method uses proof
recording, which extends the HOL Light kernel to record hierachical proof trees
alongside theorems. This method is less invasive, but requires care to manage
the size of the recorded objects. We have implemented both methods, resulting
in two systems: Tactician and HipCam
Tester periodically registers dc amplifier characteristics
Motor-driven switcher-recorder periodically registers the zero drift and gain drift signals of a dc amplifier subjected to changes in environment. A time coding method is used since several measurements are shared on a single recorder trace
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