12,185 research outputs found
MICROWAVE: A GENERIC FRAMEWORK FOR MICRO SIMULATIONBASED EX ANTE POLICY EVALUATION
This paper presents the MicroWave approach that has been developed to improve the process of modeling in the context of micro simulation. It leads to a more efficient model development, better quality of models and their output and improvement in knowledge management. A conceptual framework has been developed and translated into a hierarchical structure of GAMS program code. Besides, several software applications and other tools have been developed for support. These products are presented and some examples illustrate how MicroWave can be applied. MicroWave is especially useful in interdisciplinary research in which different persons are involved in the modeling process and when different models have to be combined.Research Methods/ Statistical Methods,
Verified AIG Algorithms in ACL2
And-Inverter Graphs (AIGs) are a popular way to represent Boolean functions
(like circuits). AIG simplification algorithms can dramatically reduce an AIG,
and play an important role in modern hardware verification tools like
equivalence checkers. In practice, these tricky algorithms are implemented with
optimized C or C++ routines with no guarantee of correctness. Meanwhile, many
interactive theorem provers can now employ SAT or SMT solvers to automatically
solve finite goals, but no theorem prover makes use of these advanced,
AIG-based approaches.
We have developed two ways to represent AIGs within the ACL2 theorem prover.
One representation, Hons-AIGs, is especially convenient to use and reason
about. The other, Aignet, is the opposite; it is styled after modern AIG
packages and allows for efficient algorithms. We have implemented functions for
converting between these representations, random vector simulation, conversion
to CNF, etc., and developed reasoning strategies for verifying these
algorithms.
Aside from these contributions towards verifying AIG algorithms, this work
has an immediate, practical benefit for ACL2 users who are using GL to
bit-blast finite ACL2 theorems: they can now optionally trust an off-the-shelf
SAT solver to carry out the proof, instead of using the built-in BDD package.
Looking to the future, it is a first step toward implementing verified AIG
simplification algorithms that might further improve GL performance.Comment: In Proceedings ACL2 2013, arXiv:1304.712
Service-sector competition, innovation and R&D
The central prediction of the Aghion et al. (2005) model is an inverted U-shaped relation between innovation and competition. The model is built on the assumption of a product market and has not yet been empirically tested on service-sector firms. Using detailed firm-level data, we find the inverse U-shaped relation to hold for both small and large service-sector firms. However, non-exporting service firms deviate from the overall pattern. A more detailed breakdown of innovation expenditures shows that the inverse U-shaped pattern holds for both intramural R&D and training, but not for extramural R&D. Finally, as competition increases, small firms tend to seek more strategic alliances with competitors while large firms tend to decrease their collaboration with competitors. To some extent, the behavior of large firms can be due to their greater capacity to handle innovation projects internally and as competition increases, so does the payoff of an edge to competitors.R&D; innovation; competition; service sector
From the Quantum Approximate Optimization Algorithm to a Quantum Alternating Operator Ansatz
The next few years will be exciting as prototype universal quantum processors
emerge, enabling implementation of a wider variety of algorithms. Of particular
interest are quantum heuristics, which require experimentation on quantum
hardware for their evaluation, and which have the potential to significantly
expand the breadth of quantum computing applications. A leading candidate is
Farhi et al.'s Quantum Approximate Optimization Algorithm, which alternates
between applying a cost-function-based Hamiltonian and a mixing Hamiltonian.
Here, we extend this framework to allow alternation between more general
families of operators. The essence of this extension, the Quantum Alternating
Operator Ansatz, is the consideration of general parametrized families of
unitaries rather than only those corresponding to the time-evolution under a
fixed local Hamiltonian for a time specified by the parameter. This ansatz
supports the representation of a larger, and potentially more useful, set of
states than the original formulation, with potential long-term impact on a
broad array of application areas. For cases that call for mixing only within a
desired subspace, refocusing on unitaries rather than Hamiltonians enables more
efficiently implementable mixers than was possible in the original framework.
Such mixers are particularly useful for optimization problems with hard
constraints that must always be satisfied, defining a feasible subspace, and
soft constraints whose violation we wish to minimize. More efficient
implementation enables earlier experimental exploration of an alternating
operator approach to a wide variety of approximate optimization, exact
optimization, and sampling problems. Here, we introduce the Quantum Alternating
Operator Ansatz, lay out design criteria for mixing operators, detail mappings
for eight problems, and provide brief descriptions of mappings for diverse
problems.Comment: 51 pages, 2 figures. Revised to match journal pape
Characterization of pure quantum states of multiple qubits using the Groverian entanglement measure
The Groverian entanglement measure, G(psi), is applied to characterize a
variety of pure quantum states |psi> of multiple qubits. The Groverian measure
is calculated analytically for certain states of high symmetry, while for
arbitrary states it is evaluated using a numerical procedure. In particular, it
is calculated for the class of Greenberger-Horne-Zeilinger states, the W states
as well as for random pure states of n qubits. The entanglement generated by
Grover's algorithm is evaluated by calculating G(psi) for the intermediate
states that are obtained after t Grover iterations, for various initial states
and for different sets of the marked states.Comment: 28 pages, 5 figure
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