279,434 research outputs found
Parameterized Uniform Complexity in Numerics: from Smooth to Analytic, from NP-hard to Polytime
The synthesis of classical Computational Complexity Theory with Recursive
Analysis provides a quantitative foundation to reliable numerics. Here the
operators of maximization, integration, and solving ordinary differential
equations are known to map (even high-order differentiable) polynomial-time
computable functions to instances which are `hard' for classical complexity
classes NP, #P, and CH; but, restricted to analytic functions, map
polynomial-time computable ones to polynomial-time computable ones --
non-uniformly!
We investigate the uniform parameterized complexity of the above operators in
the setting of Weihrauch's TTE and its second-order extension due to
Kawamura&Cook (2010). That is, we explore which (both continuous and discrete,
first and second order) information and parameters on some given f is
sufficient to obtain similar data on Max(f) and int(f); and within what running
time, in terms of these parameters and the guaranteed output precision 2^(-n).
It turns out that Gevrey's hierarchy of functions climbing from analytic to
smooth corresponds to the computational complexity of maximization growing from
polytime to NP-hard. Proof techniques involve mainly the Theory of (discrete)
Computation, Hard Analysis, and Information-Based Complexity
Time complexity and gate complexity
We formulate and investigate the simplest version of time-optimal quantum
computation theory (t-QCT), where the computation time is defined by the
physical one and the Hamiltonian contains only one- and two-qubit interactions.
This version of t-QCT is also considered as optimality by sub-Riemannian
geodesic length. The work has two aims: one is to develop a t-QCT itself based
on physically natural concept of time, and the other is to pursue the
possibility of using t-QCT as a tool to estimate the complexity in conventional
gate-optimal quantum computation theory (g-QCT). In particular, we investigate
to what extent is true the statement: time complexity is polynomial in the
number of qubits if and only if so is gate complexity. In the analysis, we
relate t-QCT and optimal control theory (OCT) through fidelity-optimal
computation theory (f-QCT); f-QCT is equivalent to t-QCT in the limit of unit
optimal fidelity, while it is formally similar to OCT. We then develop an
efficient numerical scheme for f-QCT by modifying Krotov's method in OCT, which
has monotonic convergence property. We implemented the scheme and obtained
solutions of f-QCT and of t-QCT for the quantum Fourier transform and a unitary
operator that does not have an apparent symmetry. The former has a polynomial
gate complexity and the latter is expected to have exponential one because a
series of generic unitary operators has a exponential gate complexity. The time
complexity for the former is found to be linear in the number of qubits, which
is understood naturally by the existence of an upper bound. The time complexity
for the latter is exponential. Thus the both targets are examples satisfyng the
statement above. The typical characteristics of the optimal Hamiltonians are
symmetry under time-reversal and constancy of one-qubit operation, which are
mathematically shown to hold in fairly general situations.Comment: 11 pages, 6 figure
COMPLEX INTUITIONISTIC FUZZY DOMBI PRIORITIZED AGGREGATION OPERATORS AND THEIR APPLICATION FOR RESILIENT GREEN SUPPLIER SELECTION
One of the main problems faced by resilient supply chain management is how to solve the problem of supplier selection, which is a typical multi-attribute decision-making (MADM) problem. Given the complexity of the current decision-making environment, the primary influence of this paper is to propose the theory of Dombi operational laws based on complex intuitionistic fuzzy (CIF) information. Moreover, we examined the theory of CIF Dombi prioritized averaging (CIFDPA) and CIF weighted Dombi prioritized averaging (CIFWDPA), where these operators are the modified version of the prioritized aggregation operators and Dombi aggregation operators for fuzzy, intuitionistic fuzzy, complex fuzzy and complex intuitionistic fuzzy information. Some reliable properties for the above operators are also established. Furthermore, to state the art of the proposed operators, an application example in the presence of the invented operators is evaluated for managing resilient green supplier selection problems. Finally, through comparative analysis with mainstream technologies, we provide some mechanism explanations for the proposed method to show the supremacy and worth of the invented theory
Operator learning with PCA-Net: upper and lower complexity bounds
PCA-Net is a recently proposed neural operator architecture which combines
principal component analysis (PCA) with neural networks to approximate
operators between infinite-dimensional function spaces. The present work
develops approximation theory for this approach, improving and significantly
extending previous work in this direction: First, a novel universal
approximation result is derived, under minimal assumptions on the underlying
operator and the data-generating distribution. Then, two potential obstacles to
efficient operator learning with PCA-Net are identified, and made precise
through lower complexity bounds; the first relates to the complexity of the
output distribution, measured by a slow decay of the PCA eigenvalues. The other
obstacle relates to the inherent complexity of the space of operators between
infinite-dimensional input and output spaces, resulting in a rigorous and
quantifiable statement of a "curse of parametric complexity", an
infinite-dimensional analogue of the well-known curse of dimensionality
encountered in high-dimensional approximation problems. In addition to these
lower bounds, upper complexity bounds are finally derived. A suitable
smoothness criterion is shown to ensure an algebraic decay of the PCA
eigenvalues. Furthermore, it is shown that PCA-Net can overcome the general
curse for specific operators of interest, arising from the Darcy flow and the
Navier-Stokes equations
Foundations of Online Structure Theory II: The Operator Approach
We introduce a framework for online structure theory. Our approach
generalises notions arising independently in several areas of computability
theory and complexity theory. We suggest a unifying approach using operators
where we allow the input to be a countable object of an arbitrary complexity.
We give a new framework which (i) ties online algorithms with computable
analysis, (ii) shows how to use modifications of notions from computable
analysis, such as Weihrauch reducibility, to analyse finite but uniform
combinatorics, (iii) show how to finitize reverse mathematics to suggest a fine
structure of finite analogs of infinite combinatorial problems, and (iv) see
how similar ideas can be amalgamated from areas such as EX-learning, computable
analysis, distributed computing and the like. One of the key ideas is that
online algorithms can be viewed as a sub-area of computable analysis.
Conversely, we also get an enrichment of computable analysis from classical
online algorithms
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