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Characterizing finite subspaces

B.L Rothschild, J.H Van Lint
1974 Journal of combinatorial theory. Series A  
In this paper we study generalizations of the following question: Is a subspace of a projective or affine space characterized by the cardinalities of intersections with all hyperplanes?  ...  If r > 1 then A(n, q; k, r, 1) characterizes k-subspaces of A ?Z-THEOREM 3. If r > -1 then P(n, q; k, r, 1) characterizes k-subspaces ofP7l. THEOREM 4.  ...  If j > 1 and (q,j) # (2, n -1) then A(n, q; k, 0, j) characterizes k-subspaces of A,, . THEOREM 5. If j > 1 then P(n, q; k, 0, j) characterizes k-s&paces of P ?  ... 
doi:10.1016/0097-3165(74)90075-2 fatcat:pd34tlzkajabjmejjcan6dniyy

Characterization of finite dimensional subspaces of complex functions that are invariant under linear differential operators [article]

Pep Mulet
2016 arXiv   pre-print
school relies on the fact that the right hand side function is the product of a polynomial and an exponential and that the linear spaces of those functions are invariant under differential operators (finite  ...  to prove that the linear spaces spanned by products of polynomial and exponentials are the only linear complex spaces that are invariant under differential operators, therefore non-homogeneous linear finite  ...  Introduction We characterize the finite dimensional subspaces of the space of complex sequences which are invariant under every linear finite differences operator as direct sums of spaces of arithmetic-geometric  ... 
arXiv:1607.05121v1 fatcat:srz2h62ydrbqvbmyhscu3tfhpe

Characterizing two-timescale nonlinear dynamics using finite-time Lyapunov exponents and subspaces

K.D. Mease, U. Topcu, E. Aykutluğ, M. Maggia
2016 Communications in nonlinear science & numerical simulation  
Finite-time Lyapunov exponents and subspaces are used to define and diagnose boundary-layer type, two-timescale behavior in the tangent linear dynamics and to determine the associated manifold structure  ...  Two-timescale behavior is characterized by a slow-fast splitting of the tangent bundle for a state space region.  ...  finite-time subspaces are converging.  ... 
doi:10.1016/j.cnsns.2015.11.021 fatcat:3twfyc6f6fczjnbikpikagroni

Characterization of best approximations in normed linear spaces of matrices by elements of finite-dimensional linear subspaces

K.K. Lau, W.O.J. Riha
1981 Linear Algebra and its Applications  
A general characterization theorem of best approximations in normed linear spaces is specialized to the linear space of real nX n matrices endowed with the spectral norm.  ...  subspace of Ml: Given the m-dimensional subspace A={A,,...  ...  ,m i=l 04 f;(x-g*)=%P(Pi) IIX-g*lIy i=l,..., THE CONJUGATE SPACE h4* Since M is finite-dimensional, its conjugate space M* is isomorphic to M itself.  ... 
doi:10.1016/0024-3795(81)90268-8 fatcat:ooejfbcotbberihgp7424xufgu

Page 6295 of Mathematical Reviews Vol. , Issue 2004h [page]

2004 Mathematical Reviews  
Let Q be a quadric defined by a quadratic form in the finite projective space Y = PG(d,q). A subspace of QO is a subspace of Y contained in Q.  ...  Van Maldeghem, “Hermitian Veroneseans over finite fields”, submitted] contains some proper- ties of Hermitian Veroneseans over finite fields, and these varieties and some of their projections are characterized  ... 

Chebyshev subspaces in the space of compact operators

David A Legg, Bruce E Scranton, Joseph D Ward
1975 Journal of Approximation Theory  
CHEBYSHEV SUBSPACES OF FINITE CODIMENSION To characterize the Chebyshev subspaces of finite codimension in g(s), we first characterize the proximinal subspaces of 9?(Z).  ...  An intrinsic characterization of the finite-dimensional Chebyshev subspaces is then obtained.  ... 
doi:10.1016/0021-9045(75)90092-1 fatcat:tdsticmqynbvnizt75aqp7g36u

Page 4698 of Mathematical Reviews Vol. , Issue 2004f [page]

2004 Mathematical Reviews  
The above characterization is given by means of some subspaces in both classes of maximal singular subspaces, dealt with in a uniform way, and assuming that just one of these subspaces is of finite rank  ...  E. (1-KSS; Manhattan, KS) Characterization of Grassmannians by one class of singular subspaces. (English summary) Ady. Geom. 3 (2003), no. 3, 227-250.  ... 

J-Self-Adjoint Extensions for a Class of Discrete Linear Hamiltonian Systems

Guojing Ren, Huaqing Sun
2013 Abstract and Applied Analysis  
The minimal and maximal subspaces are characterized, and the defect indices of the minimal subspaces are discussed.  ...  All theJ-self-adjoint subspace extensions of the minimal subspace are completely characterized in terms of the square summable solutions and boundary conditions.  ...  In the third subsection, characterizations of the maximal subspaces are established. Characterizations of the Minimal Subspaces.  ... 
doi:10.1155/2013/904976 fatcat:gchs7c6ofrhk3ifv4szs5tqhti

Chebyshev subspaces of finite codimension in spaces of continuous functions

A. L. Brown
1978 Journal of the Australian Mathematical Society  
The proof depends upon a simplification of a characterization by Garkavi of the Chebyshev subspaces of finite codimension in C(X). Subject classification (Amer. Math. Soc.  ...  Garkavi in 1967 characterized those compact metric spaces X with the property that the space C(X) of real-valued continuous functions possesses Chebyshev subspaces of fine codimension > 2.  ...  Chebyshev subspaces Garkavi's characterization of the Chebyshev subspaces of finite codimension in C(X) is as follows.  ... 
doi:10.1017/s1446788700011575 fatcat:oe5y2nqhbjec7hj45eyogpj5vi

Reflexive lattices of subspaces

K. H. Kim, F. W. Roush
1980 Proceedings of the American Mathematical Society  
We characterize finite reflexive lattices of subspaces of a finite dimensional vector space over an infinite field.  ...  A lattice of subspaces of a vector space is called reflejove if no other subspace is invariant under all linear mappings which leave invariant all subspaces of the lattice.  ...  Halmos ([2], [3]) has proposed the problem of characterizing reflexive lattices of subspaces.  ... 
doi:10.1090/s0002-9939-1980-0548075-0 fatcat:7falxalvnjbrndklm3r6ddfyty

Extension closed and cluster closed subspaces

Douglas Harris
1972 Canadian Journal of Mathematics - Journal Canadien de Mathematiques  
Among Hausdorff spaces, the closed subspaces are characterized by the property that such a subspace is extension closed] that is, every cover of the subspace extends to a cover of the entire space.  ...  A number of equivalent characterizations of extension closed subspaces can be given. A few preliminary properties must be set forth.  ...  The following characterizations of cluster closed subspaces are sometimes useful; the characterization (iii) is the source of the term cluster closed. PROPOSITION B.  ... 
doi:10.4153/cjm-1972-119-8 fatcat:ypczmm7o5rczbmhtspjyuecox4

Page 100 of Mathematical Reviews Vol. 34, Issue 1 [page]

1967 Mathematical Reviews  
Finally, he gives some | characterizations of finite-dimensional smooth Banach spaces E in terms of CebySev sets.  ...  .; Zippin, M. 588 On finite dimensional subspaces of Banach spaces. Israel J. Math. 3 (1965), 147-156.  ... 

Weak Chebyshev subspaces and $A$-subspaces of $C[a,b]$

Wu Li
1990 Transactions of the American Mathematical Society  
In this paper we show some very interesting properties of weak Chebyshev subspaces and use them to simplify Pinkus's characterization of Asubspaces of C[a, b].  ...  As a consequence we obtain that if the metric projection PG from C[a, b] onto a finite-dimensional subspace G has a continuous selection and elements of G have no common zeros on (a, b), then G is an /  ...  Then we have the following characterization of Chebyshev subspaces of Cw(K) with respect to varying weights. 5X4 WU LI Theorem 1.1. Suppose that G is a finite-dimensional subspace of C(K).  ... 
doi:10.1090/s0002-9947-1990-1010886-6 fatcat:5vigyyplebaezc3gc5tji6pud4

Page 1516 of Mathematical Reviews Vol. , Issue 85d [page]

1985 Mathematical Reviews  
spaces in L' subspaces] Trans. Amer. Math. Soc. 279 (1983), no. 2, 611-616. The space [? is said to be finitely representable in the linear space E if, for each finite-dimensional subspace X of [?  ...  A Banach space X is called an £; ,-space if each finite-dimen- sional subspace E of X is contained in another finite-dimensional subspace F of X such that the Banach- Mazur distance between F and [¢'™  ... 

The inaccessible invariant subspaces of certain $C\sb{0}$\ operators

John Daughtry
1980 Proceedings of the American Mathematical Society  
We extend the Douglas-Pearcy characterization of the inaccessible invariant subspaces of an operator on a finite-dimensional Hubert space to the cases of algebraic operators and certain C0 operators on  ...  This characterization shows that the inaccessible invariant subspaces for such an operator form a lattice. In contrast to D.  ...  Douglas and Carl Pearcy [3] have characterized the isolated invariant subspaces for T in the case of finite-dimensional H (see [9, Chapters 6 and 7], for the linear algebra used in this article): An  ... 
doi:10.1090/s0002-9939-1980-0548083-x fatcat:45x2fgpsyjhzbiqopuxubapocy
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