منابع مشابه
Non-Existence of isomorphisms between certain unitals
We show that the Ree-Tits unitals are neither classical nor isomorphic to the polar unitals found in the Coulter-Matthews planes. To this end, we determine the full automorphism groups of the (finite) Ree unitals.
متن کاملBorel structures and Borel theories
We show that there is a complete, consistent Borel theory which has no “Borel model” in the following strong sense: There is no structure satisfying the theory for which the elements of the structure are equivalence classes under some Borel equivalence relation and the interpretations of the relations and function symbols are Borel in the natural sense. We also investigate Borel isomorphisms be...
متن کاملON THE EXISTENCE OF PERIODIC SOLUTIONS FOR CERTAIN NON-LINEAR DIFFERENTIAL EQUATIONS
Here we consider some non-autonomous ordinary differential equations of order n and present some results and theorems on the existence of periodic solutions for them, which are sufficient conditions, section 1. Also we include generalizations of these results to vector differential equations and examinations of some practical examples by numerical simulation, section 2. For some special cases t...
متن کاملEXISTENCE OF FIXED POINTS OF CERTAIN CLASSES OF NONLINEAR MAPPINGS
In this study, we introduce the classes of $phi$-strongly pseudocontractive mappings in the intermediate sense and generalized $Phi$-pseudocontractive mappings in the intermediate sense and prove the existence of fixed points for those maps. The results generalise the results of several authors in literature including Xiang [Chang He Xiang, Fixed point theorem for generalized $Phi$-pseudocontra...
متن کاملThe non-existence of certain regular graphs of girth 5
Letf‘(k, g) be the minimum number of vertices that a graph with valency k and girth g can have. The results of Hoffman and Singleton [3] included f(k. 5) > k* + 1 for all k. except k = 2, 3, 7, 57 (it is unknown if the statement is true for k = 57). Brown proved in [2] that f(k, 5) > k2 + 2 for all k with the above exceptions; this statement is contained in a far more general theorem that has r...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Fundamenta Mathematicae
سال: 1970
ISSN: 0016-2736,1730-6329
DOI: 10.4064/fm-69-3-241-242