منابع مشابه
The Coincidence Problem
Discrete point sets S such as lattices or quasiperiodic Delone sets may permit, beyond their symmetries, certain isometries R such that S ∩ RS is a subset of S of finite density. These are the so-called coincidence isometries. They are important in understanding and classifying grain boundaries and twins in crystals and quasicrystals. It is the purpose of this contribution to introduce the corr...
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Let M be a set and F a family of its subsets. F is said by E. W. MILLER [5] to possess property B if there exists a subset K of M so that no set of the family F is contained either in K or in K (K is the complement of K in M) . HAJNAL and 1 [2] recently published a paper on the property B and its generalisations . One of the unsolved problems we state asks : What is the smallest integer in (n) ...
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متن کاملA combinatorial problem in geometry
© Foundation Compositio Mathematica, 1935, tous droits réservés. L’accès aux archives de la revue « Compositio Mathematica » (http: //http://www.compositio.nl/) implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/legal.php). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier ...
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A framework is suggested in which the energy integrals of the Friedmann cosmology are identified as genuine time-independent physical characteristics for both vacuum and non-vacuum forms of cosmic energy. The integrals are found to be numerically coincident within two orders of magnitude. It is assumed that this coincidence reveals a symmetry that relates vacuum to non-vacuum forms of cosmic en...
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ژورنال
عنوان ژورنال: Bulletin of the American Mathematical Society
سال: 1967
ISSN: 0002-9904
DOI: 10.1090/s0002-9904-1967-11863-9