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On Using Unsatisfiability for Solving Maximum Satisfiability
Maximum Satisfiability (MaxSAT) is a well-known optimization pro- blem, with
several practical applications. The most widely known MAXS AT algorithms are
ineffective at solving hard problems instances from practical application
domains. Recent work proposed using efficient Boolean Satisfiability (SAT)
solvers for solving the MaxSAT problem, based on identifying and eliminating
unsatisfiable subformulas. However, these algorithms do not scale in practice.
This paper analyzes existing MaxSAT algorithms based on unsatisfiable
subformula identification. Moreover, the paper proposes a number of key
optimizations to these MaxSAT algorithms and a new alternative algorithm. The
proposed optimizations and the new algorithm provide significant performance
improvements on MaxSAT instances from practical applications. Moreover, the
efficiency of the new generation of unsatisfiability-based MaxSAT solvers
becomes effectively indexed to the ability of modern SAT solvers to proving
unsatisfiability and identifying unsatisfiable subformulas
Cooling and heating by adiabatic magnetization in the NiMnIn magnetic shape memory alloy
We report on measurements of the adiabatic temperature change in the inverse
magnetocaloric NiMnIn alloy. It is shown that this alloy
heats up with the application of a magnetic field around the Curie point due to
the conventional magnetocaloric effect. In contrast, the inverse magnetocaloric
effect associated with the martensitic transition results in the unusual
decrease of temperature by adiabatic magnetization. We also provide
magnetization and specific heat data which enable to compare the measured
temperature changes to the values indirectly computed from thermodynamic
relationships. Good agreement is obtained for the conventional effect at the
second-order paramagnetic-ferromagnetic phase transition. However, at the first
order structural transition the measured values at high fields are lower than
the computed ones. Irreversible thermodynamics arguments are given to show that
such a discrepancy is due to the irreversibility of the first-order martensitic
transition.Comment: 5 pages, 4 figures. Accepted for publication in the Physical Review
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