Tilting with additional structure: twosided tilting complexes

1998 ◽  
pp. 105-149 ◽  
Author(s):  
Alexander Zimmermann
Keyword(s):  
Additional Structure

scholarly journals DECOMPOSITION OF UNITARY MATRICES AND QUANTUM GATES

2013 ◽  
Vol 11 (01) ◽  
pp. 1350015 ◽  
Author(s):  
CHI-KWONG LI ◽  
REBECCA ROBERTS ◽  
XIAOYAN YIN
Keyword(s):  
General Scheme ◽  
Quantum Gate ◽  
Quantum Gates ◽  
Unitary Matrix ◽  
Additional Structure ◽  
Unitary Matrices ◽  
Decomposition Scheme ◽  
Single Qubit ◽  
Matlab Program

A general scheme is presented to decompose a d-by-d unitary matrix as the product of two-level unitary matrices with additional structure and prescribed determinants. In particular, the decomposition can be done by using two-level matrices in d - 1 classes, where each class is isomorphic to the group of 2 × 2 unitary matrices. The proposed scheme is easy to apply, and useful in treating problems with the additional structural restrictions. A Matlab program is written to implement the scheme, and the result is used to deduce the fact that every quantum gate acting on n-qubit registers can be expressed as no more than 2n-1(2n-1) fully controlled single-qubit gates chosen from 2n-1 classes, where the quantum gates in each class share the same n - 1 control qubits. Moreover, it is shown that one can easily adjust the proposed decomposition scheme to take advantage of additional structure evolving in the process.

On a topological construction of Juhasz and Shelah

1992 ◽  
Vol 57 (1) ◽  
pp. 166-171
Author(s):  
Dan Velleman
Keyword(s):  
Topological Space ◽  
Additional Structure ◽  
Homogeneous Set ◽  
Stationary Set ◽  
Topological Construction

In [2], Juhasz and Shelah use a forcing argument to show that it is consistent with GCH that there is a 0-dimensional T2 topological space X of cardinality ℵ3 such that every partition of the triples of X into countably many pieces has a nondiscrete (in the topology) homogeneous set. In this paper we will show how to construct such a space using a simplified (ω2, 1)-morass with certain additional structure added to it. The additional structure will be a slight strengthening of a built-in ◊ sequence, analogous to the strengthening of ordinary ◊k to ◊S for a stationary set S ⊆ k.Suppose 〈〈θα∣ ∝ ≤ ω2〉, 〈∝β∣α < β ≤ ω2〉〉 is a neat simplified (ω2, 1)-morass (see [3]). Let ℒ be a language with countably many symbols of all types, and suppose that for each α < ω2, α is an ℒ-structure with universe θα. The sequence 〈α∣α < ω2 is called a built-in ◊ sequence for the morass if for every ℒ-structure with universe ω3 there is some α < ω2 and some f ∈αω2 such that f(α) ≺ , where f(α) is the ℒ-structure isomorphic to α under the isomorphism f. We can strengthen this slightly by assuming that α is only defined for α ∈ S, for some stationary set S ⊆ ω2. We will then say that is a built-in ◊ sequence on levels in S if for every ℒ-structure with universe ω3 there is some α ∈ S and some f ∈ αω2 such that f(α) ≺ .

scholarly journals Global Properties of Eigenvalues of Parametric Rank One Perturbations for Unstructured and Structured Matrices

2021 ◽  
Vol 15 (3) ◽  
Author(s):  
André C. M. Ran ◽  
Michał Wojtylak
Keyword(s):  
Unit Circle ◽  
Structured Matrices ◽  
Additional Structure ◽  
General Properties ◽  
Global Properties ◽  
Classes Of Matrices ◽  
Rank One

AbstractGeneral properties of eigenvalues of $$A+\tau uv^*$$ A + τ u v ∗ as functions of $$\tau \in {\mathbb {C} }$$ τ ∈ C or $$\tau \in {\mathbb {R} }$$ τ ∈ R or $$\tau ={{\,\mathrm{{e}}\,}}^{{{\,\mathrm{{i}}\,}}\theta }$$ τ = e i θ on the unit circle are considered. In particular, the problem of existence of global analytic formulas for eigenvalues is addressed. Furthermore, the limits of eigenvalues with $$\tau \rightarrow \infty $$ τ → ∞ are discussed in detail. The following classes of matrices are considered: complex (without additional structure), real (without additional structure), complex H-selfadjoint and real J-Hamiltonian.

Dynamic programming and gambling models

1974 ◽  
Vol 6 (03) ◽  
pp. 593-606 ◽  
Author(s):  
Sheldon M. Ross
Keyword(s):  
Dynamic Programming ◽  
Additional Structure ◽  
Expected Time ◽  
Playing Time

Dynamic programming is used to solve some simple gambling models. In particular we consider the situation where an individual may bet any integral amount not greater than his fortune and he will win this amount with probability p or lose it with probability 1 — p. It is shown that if p ≧ ½ then the timid strategy (always bet one dollar) both maximizes the probability of ever reaching any preassigned fortune, and also stochastically maximizes the time until the bettor becomes broke. Also, if p ≦ ½ then the timid strategy while not stochastically maximizing the playing time does maximize the expected playing time. We also consider the same model but with the additional structure that the bettor need not gamble but may instead elect to work for some period of time. His goal is to minimize the expected time until his fortune reaches some preassigned goal. We show that if p ≦ ½ then (i) always working is optimal, and (ii) among those strategies that only allow working when the bettor is broke it is the bold strategy that is optimal

Systematic prediction of new ferroelectrics in space group R3. II

2007 ◽  
Vol 63 (2) ◽  
pp. 257-269 ◽  
Author(s):  
S. C. Abrahams
Keyword(s):  
Inorganic Crystal Structure Database ◽  
Additional Structure ◽  
Stability Range ◽  
Acta Cryst ◽  
Space Group ◽  
Structure Database ◽  
Inorganic Crystal ◽  
Crystal Class ◽  
Thermal Stability Range ◽  
Crystal Structure Database

Release 2006/1 of the Inorganic Crystal Structure Database contains 155 entries under space group R3. Atomic coordinate analysis of the first 81 structures, with 52 different structure types, in Part I [Abrahams (2006). Acta Cryst. B62, 26–41] identified a total of 18 new types that satisfy the structural criteria for ferroelectricity, five that are more likely to have or undergo a transition to 3m symmetry, 19 more likely to be or undergo a transition to nonpolar symmetry and ten with a lower property predictability. Coordinate analysis of the remaining 71 entries with 54 different structure types in Part II leads to 11 materials including Al4B6O15, PbTa3(PO4)(P2O7)3.5, the KCd4Ga5S12 family, the LiZnPO4 family, Ca3Nb1.95O8V0.05 and Mn4Ta2O9 as new candidates which satisfy the structural criteria, together with the three known ferroelectrics Na3MoO3F3, Pb2ScTaO6, and RbTi2(PO4)3 at 6.2 GPa. Two additional ferroelectric predictions are at a lower level of confidence. The analysis also reveals nine materials, two of which are isostructural, that more likely belong or are capable of undergoing a transition to crystal class 3m. There are 14 additional structure types which are more likely to be nonpolar or undergo a transition to nonpolarity, ten have reduced predictive properties, with a further nine for which the space group is expected to remain R3 over the full thermal stability range. The increasing use of methods for identifying overlooked inversion centers in structural determinations may be extended by using coordinate analysis for detecting additional commonly overlooked symmetry elements.

scholarly journals Linear mappings between topological vector spaces

1972 ◽  
Vol 14 (1) ◽  
pp. 105-118
Author(s):  
B. D. Craven
Keyword(s):  
Inductive Limit ◽  
Vector Spaces ◽  
Continuous Linear ◽  
Additional Structure ◽  
Normed Spaces ◽  
Topological Vector Spaces ◽  
Locally Convex

If A and B are locally convex topological vector spaces, and B has certain additional structure, then the space L(A, B) of all continuous linear mappings of A into B is characterized, within isomorphism, as the inductive limit of a family of spaces, whose elements are functions, or measures. The isomorphism is topological if L(A, B) is given a particular topology, defined in terms of the seminorms which define the topologies of A and B. The additional structure on B enables L(A, B) to be constructed, using the duals of the normed spaces obtained by giving A the topology of each of its seminorms separately.

Some Empirical Results Concerning Causal Learning and Representation

2021 ◽  
pp. 169-226
Author(s):  
James Woodward
Keyword(s):  
Young Children ◽  
Nonhuman Primate ◽  
Causal Learning ◽  
Additional Structure ◽  
Empirical Results ◽  
Adult Human ◽  
Causal Representation ◽  
Adult Humans ◽  
Causal Cognition ◽  
Over Time

This chapter explores some empirical results bearing on the descriptive and normative adequacy of different accounts of causal learning and representation. It begins by contrasting associative accounts with accounts that attribute additional structure to causal representation, arguing in favor of the latter. Empirical results supporting the claim that adult humans often reason about causal relationships using interventionist counterfactuals are presented. Contrasts between human and nonhuman primate causal cognition are also discussed, as well as some experiments concerning causal cognition in young children. A proposal about what is involved in having adult human causal representations is presented and some issues about how these might develop over time are explored.

scholarly journals On galaxy rotation curves from a continuum mechanics approach to modified gravity

2018 ◽  
Vol 27 (02) ◽  
pp. 1850007 ◽  
Author(s):  
Christian G. Böhmer ◽  
Nicola Tamanini ◽  
Matthew Wright
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Continuum Mechanics ◽  
Modified Gravity ◽  
Galactic Rotation ◽  
Dark Matter Halos ◽  
Additional Structure ◽  
Rotation Curves ◽  
Small Deviations ◽  
Galaxy Rotation Curves

We consider a modification of General Relativity motivated by the treatment of anisotropies in Continuum Mechanics. The Newtonian limit of the theory is formulated and applied to galactic rotation curves. By assuming that the additional structure of spacetime behaves like a Newtonian gravitational potential for small deviations from isotropy, we are able to recover the Navarro–Frenk–White profile of dark matter halos by a suitable identification of constants. We consider the Burkert profile in the context of our model and also discuss rotation curves more generally.

Mixing for invertible dynamical systems with infinite measure

2015 ◽  
Vol 15 (02) ◽  
pp. 1550012 ◽  
Author(s):  
Ian Melbourne
Keyword(s):  
Dynamical Systems ◽  
Invariant Measure ◽  
Large Class ◽  
Renewal Theory ◽  
Additional Structure ◽  
Infinite Measure ◽  
Higher Order Asymptotics ◽  
Mixing Rates ◽  
Noninvertible Maps ◽  
Invent Math

In a recent paper, Melbourne and Terhesiu [Operator renewal theory and mixing rates for dynamical systems with infinite measure, Invent. Math.189 (2012) 61–110] obtained results on mixing and mixing rates for a large class of noninvertible maps preserving an infinite ergodic invariant measure. Here, we are concerned with extending these results to the invertible setting. Mixing is established for a large class of infinite measure invertible maps. Assuming additional structure, in particular exponential contraction along stable manifolds, it is possible to obtain good results on mixing rates and higher order asymptotics.

scholarly journals On quasi-classical limits of DQ-algebroids

2017 ◽  
Vol 153 (1) ◽  
pp. 41-67
Author(s):  
Paul Bressler ◽  
Alexander Gorokhovsky ◽  
Ryszard Nest ◽  
Boris Tsygan
Keyword(s):  
Classical Limit ◽  
Additional Structure

We determine the additional structure which arises on the classical limit of a DQ-algebroid.

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