Showing papers on "Unitary state published in 1998"
TL;DR: In this article, the interaction between redistributive politics at central and local levels in a federal system, and characterize the factors influencing success in redistributeive politics in both federal and unitary systems.
235 citations
TL;DR: In this paper, the authors argue that domestic politics is typically an important part of the explanation for states' foreign policies and seek to understand its influence more precisely, and they define a domestic political explanation as one in which domestic-political interactions in at least one state yield a suboptimal foreign policy relative to some normative standard.
Abstract: ▪ Abstract A significant and growing literature on international relations (IR) argues that domestic politics is typically an important part of the explanation for states' foreign policies, and seeks to understand its influence more precisely. I argue that what constitutes a “domestic-political” explanation of a state's foreign policy choices has not been clearly elaborated. What counts as a domestic-political explanation is defined by opposition to systemic or structural explanations. But these may be specified in several different ways—I spell out two—each of which implies a different concept of domestic-political explanations. If a systemic IR theory pictures states as unitary, rational actors, then a domestic-political explanation is one in which domestic-political interactions in at least one state yield a suboptimal foreign policy relative to some normative standard. Or, if a systemic IR theory pictures states as unitary, rational actors and also requires that attributes of particular states not ent...
225 citations
TL;DR: A gradient-based systematic procedure for optimizing these transformations is described that finds the largest projection of a transformed initial operator onto the target operator and, thus, the maximum spectroscopic signal.
Abstract: Experiments in coherent magnetic resonance, microwave, and optical spectroscopy control quantum-mechanical ensembles by guiding them from initial states toward target states by unitary transformation. Often, the coherences detected as signals are represented by a non-Hermitian operator. Hence, spectroscopic experiments, such as those used in nuclear magnetic resonance, correspond to unitary transformations between operators that in general are not Hermitian. A gradient-based systematic procedure for optimizing these transformations is described that finds the largest projection of a transformed initial operator onto the target operator and, thus, the maximum spectroscopic signal. This method can also be used in applied mathematics and control theory.
202 citations
TL;DR: In this article, a criterion on the triplet (G, G, ir) that the irreducible unitary representation of a group G splits into a discrete sum of unitary representations of a subgroup G when restricted to G, each of finite multiplicity is proposed.
Abstract: Let G' c G be real reductive Lie groups. This paper offers a criterion on the triplet (G, G', ir) that the irreducible unitary representation ir of G splits into a discrete sum of irreducible unitary representations of a subgroup G' when restricted to G', each of finite multiplicity. Furthermore, we shall give an upper estimate of the multiplicity of an irreducible unitary representation of G' occurring in WrIG'
107 citations
TL;DR: In this article, the quasiparticle reflection and transmission properties at normal conductor-superconductor interfaces are examined for unitary and non-unitary spin triplet pairing states.
Abstract: The quasiparticle reflection and transmission properties at normal conductor-superconductor interfaces are examined for unitary and non-unitary spin triplet pairing states recently discussed in connection with Sr
2
RuO
4
. We find resonance peaks in the Andreev reflection amplitude, which are related to surface bound states in the superconductor. They lead to conductance peak features below the quasiparticle gap in the superconductor. The symmetry of the pairing state determines the specific dependence of the peak on the angle of incidence. Based on this observation we propose a possible experiment which allows to distinguish between different superconducting states.
92 citations
TL;DR: This paper proposes a new approach that transforms the original problem into a skew-Hermitian differential system by means of the Cayley transform, and the new methods are semi-explicit, that is, no iteration is required but the solution of a certain number of linear matrix systems at each step is needed.
Abstract: In recent years some numerical methods have been developed to integrate matrix differential systems whose solutions are unitary matrices. In this paper we propose a new approach that transforms the original problem into a skew-Hermitian differential system by means of the Cayley transform. The new methods are semi-explicit, that is, no iteration is required but the solution of a certain number of linear matrix systems at each step is needed. Several numerical comparisons with known unitary integrators are reported.
80 citations
TL;DR: In this article, the problem of classifying Πu(G) would be reduced to the case G(λu) = G. In this way, each subset is identified conjecturally (Conjecture 0.6) with a collection of unitary representations of a certain subgroup of G.
Abstract: Each subset is identified conjecturally (Conjecture 0.6) with a collection of unitary representations of a certain subgroup G(λu) of G. (We will give strong evidence and partial results for this conjecture.) In this way the problem of classifying Πu(G) would be reduced (by induction on the dimension of G) to the case G(λu) = G. Before considering the general program in more detail, we describe it in the familiar case G = SL(2,R). (This example will be treated more com-
68 citations
TL;DR: In this article, the authors derive the embedding structure of unitary N = 2 minimal models and show that these representations have a degeneration of uncharged singular states and discuss the connection to the n = 2 character formulae.
34 citations
TL;DR: A unitary representation of a quiver is given by assigning to each vertex a unitary (Euclidean) vector space and to each arrow a linear mapping of the corresponding vector spaces.
29 citations
Posted Content•
TL;DR: The U.K. and U.S. systems of corporate governance are remarkably similar as discussed by the authors, however, there are several salient differences between the system, including rules on derivative litigation, and those on corporate takeovers.
Abstract: Viewed against the backdrop of European company law generally, the U.K. and U.S. systems of corporate governance are remarkably similar. However, there are several salient differences between the system, including rules on derivative litigation, and those on corporate takeovers. The U.K. has a new robust and less regulated takeover market than the U.S., while the United States is more permissive towards derivative litigation. This paper explains the differences as a function of politics. In the United States, where corporate law is dominated by state governments, the political forces aligned against hostile takeovers are quite potent, generating legislation and judicial decisions that have suppressed takeover activity. In the United Kingdom, with a more unitary system, the political forces play out differently, and the system accordingly generates rules more accommodating to unfriendly takeovers. With respect to derivative litigation, the differences stem largely from the political influence of the organized bar. Because the U.K. system does not recognize contingency fees, there is little constituency in the organized bar pushing for liberalization in the rules governing derivative litigation. In the United States, in contrast, the "common fund" doctrine permitting attorney compensation out of the amounts generated for the benefit of the corporation has created a strong interest group within the organized bar that favors a relatively liberal scope for the remedy.
27 citations
TL;DR: In this paper, the authors studied irreducible unitary representations of Uq(SO(2,1)) and Uq (SO( 2,¶3)) for q a root of unity, which are finite dimensional.
Abstract: We study irreducible unitary representations of Uq(SO(2,1)) and Uq(SO(2,¶3)) for q a root of unity, which are finite dimensional. Among others, unitary representations corresponding to all classical one-particle representations with integral weights are found for \(\), with M being large enough. In the “massless” case with spin bigger than or equal to 1 in 4 dimensions, they are unitarizable only after factoring out a subspace of “pure gauges” as classically. A truncated associative tensor product describing unitary many-particle representations is defined for \(\).
TL;DR: In this paper, the authors consider a semidirect product G = Rn×′H and its unitary representations U of the form IndG0G(p0m) where Ind is the unitary induction, p0 is in the dual group of Rn, G0 is the stability group of p0, and m is a unitary representation of G0∩H.
Abstract: We consider a semidirect product G=Rn×′H and its unitary representations U of the form IndG0G(p0m) where Ind is the unitary induction, p0 is in the dual group of Rn, G0 is the stability group of p0, and m is a unitary representation of G0∩H. We give sufficient conditions such that U defines a wavelet transform and a discrete frame.
TL;DR: The canonical transformation and its unitary counterpart which relate the rational Calogero-Moser system to the free one were constructed in this article, and the canonical transformation was shown to be a unitary transformation.
Abstract: The canonical transformation and its unitary counterpart which relate the rational Calogero-Moser system to the free one are constructed.
TL;DR: In this paper, it was shown that an irrational rotation unitary system has a complete wandering vector if and only if the von Neumann algebra generated by the unitary systems is finite and shares a cyclic vector with its commutant.
Abstract: ABSTRACI. An abstract characterization for those irrational rotation unitary systems with complete wandering subspaces is given. We prove that an irrational rotation unitary system has a complete wandering vector if and only if the von Neumann algebra generated by the unitary system is finite and shares a cyclic vector with its commutant. We solve a factorization problem of Dai and Larson negatively for wandering vector multipliers, and strengthelsl this by showing that for an irrational rotation unitary system U, every unitary operator in w* (U) is a wandering vector multiplier. Moreover, we show that there is a class of wandering vector rilultipliers, induced in a natural way by pairs of characters of the integer group 2, which fail to factor even as the product of a unitary in U' and a unitary in w*(U). Incomplete maximal wandering subspaces are also considered, and some questions are raised.
TL;DR: Most African states are unitary with political power vested in the central government as discussed by the authors, where authority is delegated to junior government officials who implement policies within rigid guidelines and no constitutional limitations constrain the central authority in its exercise of power over public activities at all levels.
Abstract: Most African states are unitary with political power vested in the central government. Laws and decisions concerning the public sector are enacted and enforced by the central government.1 Authority is delegated to junior government officials who implement policies within rigid guidelines. Provincial and district levels of government serve administrative roles but do not make laws, collect taxes, or make spending decisions.2 Strictly speaking, political power is centrally concentrated with heads of states holding the power over all public policies affecting the polity. In most African states, no constitutional limitations constrain the central authority in its exercise of power over public activities at all levels. The unitary states of Africa largely reflect the colonial legacy. European colonial powers subdivided the African continent among themselves, establishing boundaries that arbitrarily linked heterogeneous
01 Jan 1998
TL;DR: In this paper, a Hamiltonian for the generation of arbitrary pure states of the quantized electromagnetic field has been constructed based on the fact that a unitary transformation for generating number states has already been found.
Abstract: We construct a Hamiltonian for the generation of arbitrary pure states of the quantized electromagnetic field. The proposition is based upon the fact that a unitary transformation for the generation of number states has already been found. The general unitary transformation here obtained would allow the use of nonlinear interactions for the production of pure states. We discuss the applicability of this method by giving examples of generation of simple superposition states. We also compare our Hamiltonian with the one resulting from the interaction of trapped ions with two laser fields.
TL;DR: In this article, the evolution operator is decomposed into the product form of two unitary operators in such a way that one of them has the same periodicity as the Hamiltonian and the other correspond to the Floquet operator which gives the cyclic states and their associated phases over one period of the evolution.
Abstract: Using the time-dependent unitary transformation instead of the invariant operator, the solutions of SU(1, 1) and SU(2) time-dependent quantum systems are obtained. It is shown that the evolution operator is decomposed into the product form of two unitary operators in such a way that one of them has the same periodicity as the Hamiltonian and the other correspond to the Floquet operator which gives the cyclic states and their associated phases over one period of the evolution. The non-adiabatic Berry's (or Aharonov-Anandan) phases are determined totally by such a unitary transformation.
TL;DR: In this paper, a novel realization of the classical SU(2) algebra is introduced for the Dirac relativistic hydrogen atom defining a set of operators that allow the factorization of the problem.
Abstract: A novel realization of the classical SU(2) algebra is introduced for the Dirac relativistic hydrogen atom defining a set of operators that, besides, allow the factorization of the problem. An extra phase is needed as a new variable in order to define the algebra. We take advantage of the operators to solve the Dirac equation using algebraic methods. To acomplish this, a similar path to the one used in the angular momentum case is employed; hence, the radial eigenfuntions calculated comprise non unitary representations of the algebra. One of the interesting properties of such non unitary representations is that they are not labeled by integer nor by half-integer numbers as happens in the usual angular momentum representation.
Journal Article•
TL;DR: In this paper, the data of a weak C∗Hopf algebra can be encoded into a pair (H, V ) where H is a finite dimensional Hilbert space and V : H → H⊗H is a partial isometry satisfying, among others, the pentagon equation.
Abstract: We show how the data of a finite dimensional weak C∗-Hopf algebra can be encoded into a pair (H, V ) where H is a finite dimensional Hilbert space and V : H⊗H → H⊗H is a partial isometry satisfying, among others, the pentagon equation. In case of V being unitary we recover the Baaj-Skandalis multiplicative unitary of the discrete compact type. Relation with the pseudomultiplicative unitary approach proposed by J.-M. Vallin and M. Enock is also discussed.
TL;DR: In this paper, a slightly modified version of our argument combined with the Cayley transform has been used to give a proof of Simon's result for bounded self-adjoint operators with a given norm bound.
Abstract: Abstract In a paper [1], published in 1990, in a (somewhat inaccessible) conference proceedings, the authors had shown that for the unitary operators on a separable Hilbert space, endowed with the strong operator topology, those with singular, continuous, simple spectrum, with full support, forma dense ${{G}_{\delta }}$ . A similar theorem for bounded self-adjoint operators with a given normbound (omitting simplicity) was recently given by Barry Simon [2], [3], with a totally different proof. In this note we show that a slight modification of our argument, combined with the Cayley transform, gives a proof of Simon’s result, with simplicity of the spectrum added.
TL;DR: In this article, a number of theories that have been used to analyse government formation in West European parliamentary democracies and applies them to the government formation process in Japan after the 1996 general election.
Abstract: This paper takes a number of theories that have been used to analyse government formation in West European parliamentary democracies and applies them to the government formation process in Japan after the 1996 general election. These models underline the continuing importance of the LDP in the government formation process, despite the loss of its overall majority. The application of government formation models to the Japanese case also highlights the weakness of the typical assumption that sees parties as unitary actors. The paper thus concludes with some speculations as to how this assumption might usefully be relaxed to incorporate party factions, splits and fusions and thereby generate more dynamic models of the making and breaking of governments.
01 Jan 1998
TL;DR: For a locally compact (nite-dimensional) manifold M irreducible unitary representations of a group of eomorphisms were constructed in this paper with the help of a measure on M induced by the Lebesgue measure on Rn and the Riemannian metric g on M.
Abstract: For a locally compact ( nite-dimensional) manifold M irreducible unitary representations of a group of di eomorphisms were constructed in [13] with the help of a measure on M induced by the Lebesgue measure on Rn and the Riemannian metric g on M . Each group of di eomorphisms is an in nite-dimensional manifold itself. Their structure for locally compact M was investigated in [2,7]. This article is devoted to the de nition of a group of di eomorphisms of a Banach manifold and the construction its irreducible unitary representations. For this are used quasi-invariant Gaussian measures on M . In Section 2 notations and de nitions are given. Section 3 contains results about the structure of a group of di eomorphisms. Irreducible unitary representations of a group of di eomorphisms associated with a quasi-invariant measure on a Banach manifold are
01 Jan 1998
TL;DR: A chapter on "territorial politics" appeared in this paper, arguing that the United Kingdom was a unitary state, as it still is, but it was also a homogenous state.
Abstract: Before the 1960s a chapter on ‘territorial politics’ probably would not have appeared in a book of this kind. For not only was the United Kingdom a unitary state, as it still is, it was also a homogenous state. The ‘homogeneity thesis’, which was widely held by British political scientists, argued that Britain’s unitary constitution was underpinned by an increasingly uniform political culture in which religious, linguistic and national differences were overridden by differences based on social class. Hence separate discussion of the various national components of the UK was not required since these countries were becoming progressively more alike. But in the late 1960s and 1970s the emergence of nationalist movements in Scotland and Wales and of ‘the troubles’ in Northern Ireland provided a reminder of the complex, multinational nature of the UK. Its taken-for-granted unity disappeared as problems with the territorial management of Scotland, Wales and Northern Ireland by Westminster politicians pressed to the fore.
TL;DR: In this paper, the quantum logics of projections being self-adjoint with respect to a unitary operator on a Hilbert space are studied, and the notion of projection selfadjointness is introduced.
Abstract: Quantum logics of projections being self-adjointwith respect to a unitary operator on a Hilbert spaceare studied.
TL;DR: In this article, a class of unitary operators of L2(R) contained in the commutant of the Shift operator is defined, such that for any pair of multiresolution analyses of L 2(R), there exists a unitary operator in one of these classes, which maps all the scaling functions of the first analysis to the scaling function of the second analysis.
Abstract: This article provides classes of unitary operators of L2(R) contained in the commutant of the Shift operator, such that for any pair of multiresolution analyses of L2(R) there exists a unitary operator in one of these classes, which maps all the scaling functions of the first multiresolution analysis to scaling functions of the other. We use these unitary operators to provide an interesting class of scaling functions. We show that the Dai-Larson unitary parametrization of orthonormal wavelets is not suitable for the study of scaling functions. These operators give an interesting relation between low-pass filters corresponding to scaling functions, which is implemented by a special class of unitary operators acting on L2([−π, π)), which we characterize. Using this characterization we recapture Daubechies' orthonormal wavelets bypassing the spectral factorization process.