81,057 research outputs found
Introducing new constructs for data modelling and column generation in LP modelling languages
Through popular implementation of structured query language (SQL) and query-by-example(QBE) relational databases have become the de-facto industry standard for data modelling.We consider the indices, sets, and the declarative form of Linear Programming (LP) modelling languages and introduce new constructs which provide direct link to the database systems. The models constructed in this way are data driven and display a dynamicstructure. We then show how this approach can be naturally extended to include column generation features stated in procedural forms within an otherwise declarative modelling paradigm
An expansion in the model space in the context of utility maximization
In the framework of an incomplete financial market where the stock price
dynamics are modeled by a continuous semimartingale (not necessarily Markovian)
an explicit second-order expansion formula for the power investor's value
function - seen as a function of the underlying market price of risk process -
is provided. This allows us to provide first-order approximations of the
optimal primal and dual controls. Two specific calibrated numerical examples
illustrating the accuracy of the method are also given
Towards Formal Fault Tree Analysis using Theorem Proving
Fault Tree Analysis (FTA) is a dependability analysis technique that has been
widely used to predict reliability, availability and safety of many complex
engineering systems. Traditionally, these FTA-based analyses are done using
paper-and-pencil proof methods or computer simulations, which cannot ascertain
absolute correctness due to their inherent limitations. As a complementary
approach, we propose to use the higher-order-logic theorem prover HOL4 to
conduct the FTA-based analysis of safety-critical systems where accuracy of
failure analysis is a dire need. In particular, the paper presents a
higher-order-logic formalization of generic Fault Tree gates, i.e., AND, OR,
NAND, NOR, XOR and NOT and the formal verification of their failure probability
expressions. Moreover, we have formally verified the generic probabilistic
inclusion-exclusion principle, which is one of the foremost requirements for
conducting the FTA-based failure analysis of any given system. For illustration
purposes, we conduct the FTA-based failure analysis of a solar array that is
used as the main source of power for the Dong Fang Hong-3 (DFH-3) satellite.Comment: 1
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