• Title/Summary/Keyword: a-invariant

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Characteristic Genera of Closed Orientable 3-Manifolds

  • KAWAUCHI, AKIO
    • Kyungpook Mathematical Journal
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    • v.55 no.4
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    • pp.753-771
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    • 2015
  • A complete invariant defined for (closed connected orientable) 3-manifolds is an invariant defined for the 3-manifolds such that any two 3-manifolds with the same invariant are homeomorphic. Further, if the 3-manifold itself can be reconstructed from the data of the complete invariant, then it is called a characteristic invariant defined for the 3-manifolds. In a previous work, a characteristic lattice point invariant defined for the 3-manifolds was constructed by using an embedding of the prime links into the set of lattice points. In this paper, a characteristic rational invariant defined for the 3-manifolds called the characteristic genus defined for the 3-manifolds is constructed by using an embedding of a set of lattice points called the PDelta set into the set of rational numbers. The characteristic genus defined for the 3-manifolds is also compared with the Heegaard genus, the bridge genus and the braid genus defined for the 3-manifolds. By using this characteristic rational invariant defined for the 3-manifolds, a smooth real function with the definition interval (-1, 1) called the characteristic genus function is constructed as a characteristic invariant defined for the 3-manifolds.

Feasible and Invariant Sets For Input Constrained Linear Parameter Varying Systems

  • Lee, Young-Il
    • 제어로봇시스템학회:학술대회논문집
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    • 2003.10a
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    • pp.1911-1916
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    • 2003
  • Parameter set of an LPV system is divided into a number of subsets so that robust feedback gains may be designed for each subset of parameters. A concept of quasi-invariant set is introduced, which allows finite steps of delay in reentrance to the set. A feasible and positively invariant set with respect to a gain-scheduled state feedback control can be easily obtained from the quasi-invariant set. A receding horizon control strategy can be derived based on this feasible and invariant set.

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An Adaptive Controller Cooperating with Fuzzy Controller for Unstable Nonlinear Time-invariant Systems (불안정 비선형 시불변 시스템을 위한 퍼지제어기가 결합된 적응제어기)

  • Dae-Young, Kim;In-Hwan, Kim;Jong-Hwa, Kim;Byung-Kyul, Lee
    • Journal of Advanced Marine Engineering and Technology
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    • v.28 no.6
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    • pp.946-961
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    • 2004
  • A new adaptive controller which combines a model reference adaptive controller (MRAC) and a fuzzy controller is developed for unstable nonlinear time-invariant systems. The fuzzy controller is used to analyze and to compensate the nonlinear time-invariant characteristics of the plant. The MRAC is applied to control the linear time-invariant subsystem of the unknown plant, where the nonlinear time-invariant plant is supposed to comprise a nonlinear time-invariant subsystem and a linear time-invariant subsystem. The stability analysis for the overall system is discussed in view of global asymptotic stability. In conclusion. the unknown nonlinear time-invariant plant can be controlled by the new adaptive control theory such that the output error of the given plant converges to zero asymptotically.

INVARIANT CUBATURE FORMULAS OVER A UNIT CUBE

  • Kim, Kyoung-Joong;Song, Man-Suk
    • Communications of the Korean Mathematical Society
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    • v.13 no.4
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    • pp.913-931
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    • 1998
  • Using invariant theory, new invariant cubature formulas over a unit cube are given by imposing a group structure on the formulas. Cools and Haegemans [Computing 40, 139-146 (1988)] constructed invariant cubature formulas over a unit square. Since there exists a problem in directly extending their ideas over the unit square which were obtained by using a concept of good integrity basis to some constructions of invariant cubature formulas over the unit cube, a Reynold operator will be used to obtain new invariant cubature formulas over the unit cube. In order to practically find integration nodes and weights for the cubature formulas, it is required to solve a system of nonlinear equations. With an IMSL subroutine DUNLSF which is used for solutions of the system of nonlinear equations, we shall give integration nodes for the new invariant cubature formulas over the unit cube depending on each degree of polynomial precision.

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ON ENDOMORPHISM RING OF H-INVARIANT MODULES

  • Bae, Soon-Sook
    • East Asian mathematical journal
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    • v.6 no.2
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    • pp.167-182
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    • 1990
  • The relationships between submodules of a module and ideals of the endomorphism ring of a module had been studied in [1]. For a submodule L of a moudle M, the set $I^L$ of all endomorphisms whose images are contained in L is a left ideal of the endomorphism ring End (M) and for a submodule N of M, the set $I_N$ of all endomorphisms whose kernels contain N is a right ideal of End (M). In this paper, author defines an H-invariant module and proves that every submodule of an H-invariant module is the image and kernel of unique endomorphisms. Every ideal $I^L(I_N)$ of the endomorphism ring End(M) when M is H-invariant is a left (respectively, right) principal ideal of End(M). From the above results, if a module M is H-invariant then each left, right, or both sided ideal I of End(M) is an intersection of a left, right, or both sided principal ideal and I itself appropriately. If M is an H-invariant module then the ACC on the set of all left ideals of type $I^L$ implies the ACC on M. Also if the set of all right ideals of type $I^L$ has DCC, then H-invariant module M satisfies ACC. If the set of all left ideals of type $I^L$ satisfies DCC, then H-invariant module M satisfies DCC. If the set of all right ideals of type $I_N$ satisfies ACC then H-invariant module M satisfies DCC. Therefore for an H-invariant module M, if the endomorphism ring End(M) is left Noetherian, then M satisfies ACC. And if End(M) is right Noetherian then M satisfies DCC. For an H-invariant module M, if End(M) is left Artinian then M satisfies DCC. Also if End(M) is right Artinian then M satisfies ACC.

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Input Constrained Receding Horizon Control Using Complex Polyhedral Invariant Region (복소형 다각형 불변영역을 이용한 입력제한 예측제어)

  • 이영일;방대인;윤태웅;김기용
    • Journal of Institute of Control, Robotics and Systems
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    • v.8 no.12
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    • pp.991-997
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    • 2002
  • The concept of feasible & invariant region plays an important role to derive closed loop stability and achie adequate performance of constrained receding horizon predictive control. In this paper, we define a complex polyhedral feasible & invariant set for all stabilizable input-constrained linear systems by using a complex transform and propose a one-norm based receding horizon control scheme using these invariant sets. In order to get a larger stabilizable set, a convex hull of invariant sets which are defined for different state feedback gains is used as a target invariant set of the constrained receding horizon control. The proposed constrained receding horizon control scheme is formulated so that it can be solved via linear programming.

RICCI CURVATURE OF SUBMANIFOLDS OF AN S-SPACE FORM

  • Kim, Jeong-Sik;Dwivedi, Mohit Kumar;Tripathi, Mukut Mani
    • Bulletin of the Korean Mathematical Society
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    • v.46 no.5
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    • pp.979-998
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    • 2009
  • Involving the Ricci curvature and the squared mean curvature, we obtain a basic inequality for a submanifold of an S-space form tangent to structure vector fields. Equality cases are also discussed. As applications we find corresponding results for almost semi-invariant submanifolds, $\theta$-slant submanifolds, anti-invariant submanifold and invariant submanifolds. A necessary and sufficient condition for a totally umbilical invariant submanifold of an S-space form to be Einstein is obtained. The inequalities for scalar curvature and a Riemannian invariant $\Theta_k$ of different kind of submanifolds of a S-space form $\tilde{M}(c)$ are obtained.

ON A FUNCTIONAL EQUATION FOR QUADRATIC INVARIANT CURVES

  • Zhang, Weinian
    • Journal of the Korean Mathematical Society
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    • v.38 no.6
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    • pp.1179-1190
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    • 2001
  • Quadratic invariant curve is one of the simplest nonlinear invariant curves and was considered by C. T. Ng and the author in order to study the one-dimensional nonlinear dynamics displayed by a second order delay differential equation with piecewise constant argument. In this paper a functional equation derived from the problem of invariant curves is discussed. Using a different method from what C. T. Ng and the author once used, we define solutions piecewisely and give results in the remaining difficult case left in C. T. Ng and the authors work. A problem of analytic extension given in their work is also answered negatively.

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WARPED PRODUCT SKEW SEMI-INVARIANT SUBMANIFOLDS OF LOCALLY GOLDEN RIEMANNIAN MANIFOLDS

  • Ahmad, Mobin;Qayyoom, Mohammad Aamir
    • Honam Mathematical Journal
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    • v.44 no.1
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    • pp.1-16
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    • 2022
  • In this paper, we define and study warped product skew semi-invariant submanifolds of a locally golden Riemannian manifold. We investigate a necessary and sufficient condition for a skew semi-invariant submanifold of a locally golden Riemannian manifold to be a locally warped product. An equality between warping function and the squared normed second fundamental form of such submanifolds is established. We also construct an example of warped product skew semi-invariant submanifolds.