A theorem in finite projective geometry and some applications to number theory

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Type: Article
Publication Date: 1938-01-01
Citations: 736
DOI: https://doi.org/10.1090/s0002-9947-1938-1501951-4

Abstract

A point in a finite projective plane PG(2, pn), may be denoted by the symbol (xi, x2, x3), where the coordinates xi, x2, x3 are marks of a Galois field of order pn, GF(pn).The symbol (0, 0, 0) is excluded, and if k is a non-zero mark of the GF(pn), the symbols (xi, Xi, x3) and (kxh kx2, kx3) are to be thought of as the same point.The totality of points whose coordinates satisfy the equation uiXi+u2x2+u3x3 = 0, where ui, w2, u3 are marks of the GF(pn), not all zero, is called a line.The plane then consists of p2n+pn+l = q points and q lines; each line contains pn + \ points, j A finite projective plane, PG(2, pn), defined in this way is Pascalian and Desarguesian ; it exists for every prime p and positive integer », and there is only one such PG(2, pn) for a given p and » (VB, p. 247, VY, p. 151).Let Ao be a point of a given PG(2, pn), and let C be a collineation of the points of the plane.(A collineation is a 1-1 transformation carrying points into points and lines into lines.)Suppose C carries A o into A\, Ax into * Presented to the Society, October 27, 1934, under a different title;

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The papers comprising this volume explore various fields of number theory, including: the congruent property of solutions of quadratic Diophantine equations, K-groups over the ring of integers of number fields, … The papers comprising this volume explore various fields of number theory, including: the congruent property of solutions of quadratic Diophantine equations, K-groups over the ring of integers of number fields, L-functions of global function fields, automorphic forms, p-adic representations, and more. Applications of number theory, as in design and coding theory, are also explored. The research found in this volume can be seen as a reflection of the influence of Professor Keqin Feng upon the development of number theory studies in China, and this volume is therefore dedicated to him. Number Theory and Related Areas is a valuable reference for experts in these fields, as well as an excellent introduction for graduate students.
We collect in this chapter some elementary number-theoretical tools. In particular, Zsigmondy’s theorem on primitive prime divisors and related issues will be useful for the investigations to come later in … We collect in this chapter some elementary number-theoretical tools. In particular, Zsigmondy’s theorem on primitive prime divisors and related issues will be useful for the investigations to come later in this book. Specific Diophantine equations are also of interest in the succeeding chapters, but will be studied in detail only when they specifically occur.
Problem 3.4 Prove that the sum of any n entries of the table $$\begin{array}{c@{\quad}c@{\quad}c@{\quad}c@{\quad}c}1 & \frac{1}{2} & \frac{1}{3} & \ldots & \frac{1}{n}\\[4pt]\frac{1}{2} & \frac{1}{3} & \frac{1}{4} & \ldots & \frac{1}{n+1}\\[4pt]\vdots … Problem 3.4 Prove that the sum of any n entries of the table $$\begin{array}{c@{\quad}c@{\quad}c@{\quad}c@{\quad}c}1 & \frac{1}{2} & \frac{1}{3} & \ldots & \frac{1}{n}\\[4pt]\frac{1}{2} & \frac{1}{3} & \frac{1}{4} & \ldots & \frac{1}{n+1}\\[4pt]\vdots & & & & \\[4pt]\frac{1}{n} & \frac{1}{n+1} & \frac{1}{n+2} & \ldots & \frac{1}{2n-1}\end{array}$$ situated in different rows and different columns is not less than 1.
When we used the computer to add up the first 1ØØØ odd numbers (Chapter 9) and to build our odd hexmas tree (Chapter 12), we told the computer what was … When we used the computer to add up the first 1ØØØ odd numbers (Chapter 9) and to build our odd hexmas tree (Chapter 12), we told the computer what was even or odd. Now we pose the problem: how do we teach our 64 to figure for itself whether a given integer is even or odd? The key to this problem is to make the computer look for some property of the integer in question. In other words, if an integer satisfies one condition, it must be odd; if it satisfies another, it must be even.
We say an integer b evenly divides another integer c if c/b is a whole number. Actually, nobody in mathematics ever says that b “evenly divides” c – people just … We say an integer b evenly divides another integer c if c/b is a whole number. Actually, nobody in mathematics ever says that b “evenly divides” c – people just say b “divides” c. Another way to say the same thing is to say that b is a divisor of c. The divisors of c are the numbers that (evenly) divide c. Finally, one can also say that b is divisible by c.
Abstract In this chapter, we continue a study of numbers in all their grandness and diversity. As we have seen, there are many important and distinct number systems, including the … Abstract In this chapter, we continue a study of numbers in all their grandness and diversity. As we have seen, there are many important and distinct number systems, including the natural numbers, the integers, the rationals, the reals, and the complex numbers. We consider each of these number systems from both a computational and a theoretical point of view, developing insights that provide a competent understanding of each one. We begin with a special type of integer known as a prime number. Prime numbers can be thought of as the basic building blocks in the multiplicative structure of the integers. Many of the world’s greatest mathematicians have devoted significant effort to exploring and understanding primes, including Euclid, Pierre de Fermat, Leonhard Euler, Carl Friedrich Gauss, Peter Lejeune Dirichlet, and Georg Bernhard Riemann. Through these collective efforts, mathematicians have developed a sound understanding of both the prime numbers and the integers. At the same time, many questions about these integers remain open (or unsolved); we introduce some of these intriguing questions that continue to inspire and challenge mathematicians.
Many Olympiad problems refer to arrays of numbers. Let us start with some examples. Many Olympiad problems refer to arrays of numbers. Let us start with some examples.
This chapter is concerned with the properties of the set of integers {…, −2, −1, 0, 1, 2, …} under the arithmetic operations of addition and multiplication. We shall usually … This chapter is concerned with the properties of the set of integers {…, −2, −1, 0, 1, 2, …} under the arithmetic operations of addition and multiplication. We shall usually denote the set of integers by ℤ. We shall assume that you are acquainted with the elementary arithmetical properties of the integers. By the end of this chapter you should be able to solve the following problems.
<italic>Number Theory: A Very Short Introduction</italic> explains the branch of mathematics primarily concerned with the counting numbers, 1, 2, 3, …. Long considered one of the most ‘beautiful’ areas of … <italic>Number Theory: A Very Short Introduction</italic> explains the branch of mathematics primarily concerned with the counting numbers, 1, 2, 3, …. Long considered one of the most ‘beautiful’ areas of mathematics, number theory dates back over two millennia to the Ancient Greeks, but has seen some startling new developments in recent years. Trailblazers in the field include mathematicians Euclid of Alexandria, Pierre de Fermat, Leonhard Euler, and Carl Friedrich Gauss. Number theory has intrigued and attracted amateurs and professionals alike for thousands of years, appearing in both recreational contexts (puzzles) and practical concerns (cryptography). Some problems in number theory are easy, whereas others are notorious with no known solutions to date.
Algorithmic complexity 26 Continued fractions 45 Multiplication 26 Rational approximation 48 Exponentiation 28 Modular polynomial equations 51 Euclid’s algorithm 30 Cantor–Zassenhaus 52 Primality 31 Equations modulo p 53 Quadratic nonresidues … Algorithmic complexity 26 Continued fractions 45 Multiplication 26 Rational approximation 48 Exponentiation 28 Modular polynomial equations 51 Euclid’s algorithm 30 Cantor–Zassenhaus 52 Primality 31 Equations modulo p 53 Quadratic nonresidues 36 Chinese remainder theorem 57 Factoring, Pollard 36 Quadratic extensions 57 Discrete logarithms 38 Cipolla 58 Modular square roots 40 Lucas–Lehmer 59 Diophantine equations 42 Units in quadratic fields 61 Euclid’s algorithm 43 Smith–Cornacchia 64 Extended Euclid 43 Bibliography 66
The existence of a primitive element of $GF(q)$ with certain properties is used to prove that all cycles that could theoretically be embedded in $AG(2,q)$ and $PG(2,q)$ can, in fact, … The existence of a primitive element of $GF(q)$ with certain properties is used to prove that all cycles that could theoretically be embedded in $AG(2,q)$ and $PG(2,q)$ can, in fact, be embedded there (i.e. these planes are `pancyclic'). We also study embeddings of wheel and gear graphs in arbitrary projective planes.
For any integer h ⩾ 2 , a set A of integers is called a B h -set if all sums a 1 + ⋯ + a h , with … For any integer h ⩾ 2 , a set A of integers is called a B h -set if all sums a 1 + ⋯ + a h , with a 1 , … , a h ∈ A and a 1 ⩽ ⋯ ⩽ a h , are distinct. We obtain essentially sharp asymptotic bounds for the number of B h -sets of a given cardinality that are contained in the interval { 1 , ⋯ , n } . As a consequence of these bounds, we determine, for any integer m ⩽ n , the cardinality of the largest B h -set contained in a typical m-element subset of { 1 , … , n } .
Abstract Quasi difference sets are introduced as a tool to produce partial linear spaces. We characterize geometry and automorphisms of configurations decomposable into components induced by quasi difference sets. In … Abstract Quasi difference sets are introduced as a tool to produce partial linear spaces. We characterize geometry and automorphisms of configurations decomposable into components induced by quasi difference sets. In particular, we are interested in series of cyclically inscribed copies of a fixed configuration.
Groups defined by presentations for which the components of the corresponding star graph are the incidence graphs of generalized polygons are of interest as they are small cancellation groups that … Groups defined by presentations for which the components of the corresponding star graph are the incidence graphs of generalized polygons are of interest as they are small cancellation groups that – via results of Edjvet and Vdovina – are fundamental groups of polyhedra with the generalized polygons as links and so act on Euclidean or hyperbolic buildings; in the hyperbolic case the groups are SQ-universal. A cyclic presentation of a group is a presentation with an equal number of generators and relators that admits a particular cyclic symmetry. We obtain a classification of the concise cyclic presentations where the components of the corresponding star graph are generalized polygons. The classification reveals that both connected and disconnected star graphs are possible and that only generalized triangles (i.e. incidence graphs of projective planes) and regular complete bipartite graphs arise as the components. We list the presentations that arise in the Euclidean case and show that at most two of the corresponding groups are not SQ-universal (one of which is not SQ-universal, the other is unresolved). We obtain results that show that many of the SQ-universal groups are large.
We collect the main construction methods for Golomb rulers available in the literature along with their proofs.In particular, we demonstrate that the Bose-Chowla method yields Golomb rulers that appear as … We collect the main construction methods for Golomb rulers available in the literature along with their proofs.In particular, we demonstrate that the Bose-Chowla method yields Golomb rulers that appear as the main diagonalof a special subfamily of Golomb Costas arrays. We also show that Golomb rulers can be composed to yield longer Golomb rulers.
For a prime power q, we show that a cyclic relative difference set with parameters (q/sup n/-1/q-1,q-1,q/sup n-1/,q/sup n-2/) can be constructed from a d-homogeneous function from F/sub q//sup n//spl … For a prime power q, we show that a cyclic relative difference set with parameters (q/sup n/-1/q-1,q-1,q/sup n-1/,q/sup n-2/) can be constructed from a d-homogeneous function from F/sub q//sup n//spl bsol/{0} onto F/sub q/ with difference-balanced property, where F/sub q//sup n/ is the finite field with q/sup n/ elements. This construction method enables us to construct several new cyclic relative difference sets with parameters (p/sup n/-1/p/sup l/-1,p/sup l/-1,p/sup n-l/,p/sup n-2l/) from p-ary sequences of period p/sup n/-1 with ideal autocorrelation property introduced by Helleseth and Gong. Using a lifting idea, other new cyclic relative difference sets can be constructed from the Helleseth-Gong (HG) sequences. Also, the 3-ranks and the trace representation of the characteristic sequences of cyclic relative difference sets from a specific class of ternary HG sequences and ternary Lin sequences are derived.
A set of positive integers A is called a B h [g] set if there are at most g different sums of h elements from A with the same result.This … A set of positive integers A is called a B h [g] set if there are at most g different sums of h elements from A with the same result.This definition has a generalization to abelian groups and the main problem related to this kind of sets, is to find B h [g] maximal sets i.e. those with larger cardinality.We construct B h [g] modular sets from B h modular sets using homomorphisms and analyze the constructions of B h sets by Bose and Chowla, Ruzsa, and Gómez and Trujillo look at for the suitable homomorphism that allows us to preserve the cardinal of this types of sets.
A $k$-radius sequence over an $n$-element alphabet $A$ is a sequence in which every two elements of $A$ appear within distance at most $k$ (where the distance is defined as … A $k$-radius sequence over an $n$-element alphabet $A$ is a sequence in which every two elements of $A$ appear within distance at most $k$ (where the distance is defined as the difference of indices). By a $k$-radius sequence over an $n$-element alphabet $A$ we mean a sequence in which every two elements of $A$ appear within distance at most $k$. The problem of constructing shortest possible $k$-radius sequences, motivated by some problems occurring in large data transfer, has been studied by several authors recently. In this paper we present an explicit construction of “short” $k$-radius sequences for some values of $k$ and $n$. This construction allows us to find 2-radius sequences of the shortest possible length for all but very special values of $n$. For all $n$ we construct 2-radius sequences whose length differs from the length of the shortest one only by a constant. Moreover, we construct shortest possible $k$-radius sequences when $n=2k^2+2k+1$ and $k$ is a power of a prime. Our construction depends on the existence of some other sequences that we call $k$-perfect and $k$-additive. We investigate these sequences as they seem to be interesting in themselves.
James Singer [ 12 ] has shown that there exists a collineation which is transitive on the ( t - 1)-spaces, that is, ( t - 1)-dimensional linear subspaces, of … James Singer [ 12 ] has shown that there exists a collineation which is transitive on the ( t - 1)-spaces, that is, ( t - 1)-dimensional linear subspaces, of PG ( t , p n ). In this paper we shall generalize this result showing that there exist t - r collineations which together are transitive on the s-spaces of PG ( t , p n ). An explicit construction will be given for such a set of collineations with the aid of primitive elements of Galois fields. This leads to a calculus for the linear subspaces of finite projective geometries.
Abstract In this paper we prove that a Rédei blocking set with two Rédei lines defines a quasigroup. In the first case by using quasigroups we determine the maximum number … Abstract In this paper we prove that a Rédei blocking set with two Rédei lines defines a quasigroup. In the first case by using quasigroups we determine the maximum number of non-isomorphic Rédei blocking sets with two Rédei lines.
We consider quadruples of positive integers $(a,b,m,n)$ with $a\leq b$ and $m\leq n$ such that any proper edge-coloring of the complete bipartite graph $K_{m,n}$ contains a rainbow $K_{a,b}$ subgraph. We … We consider quadruples of positive integers $(a,b,m,n)$ with $a\leq b$ and $m\leq n$ such that any proper edge-coloring of the complete bipartite graph $K_{m,n}$ contains a rainbow $K_{a,b}$ subgraph. We show that any such quadruple with $a\leq m$ and $n&gt;(a^2-a+1)(b-1)$ satisfies this property. We also show that the quadruple $(2,3,3,6)$ satisfies this property. We end with a conjecture.
Abstract It is easily shown that every digraph with m edges has a directed cut of size at least m /4, and that 1/4 cannot be replaced by any larger … Abstract It is easily shown that every digraph with m edges has a directed cut of size at least m /4, and that 1/4 cannot be replaced by any larger constant. We investigate the size of the largest directed cut in acyclic digraphs, and prove a number of related results concerning cuts in digraphs and acyclic digraphs. © 2006 Wiley Periodicals, Inc. J Graph Theory 55: 1–13, 2007
Abstract We prove that a finite set of natural numbers J satisfies that $J\cup \{0\}$ is not Sidon if and only if for any operator T , the disjoint hypercyclicity … Abstract We prove that a finite set of natural numbers J satisfies that $J\cup \{0\}$ is not Sidon if and only if for any operator T , the disjoint hypercyclicity of $\{T^j:j\in J\}$ implies that T is weakly mixing. As an application we show the existence of a non-weakly mixing operator T such that $T\oplus T^2\oplus\cdots \oplus T^n$ is hypercyclic for every n .
One reason why Combinatorics has been slow to become accepted as part of mainstream Mathematics is the common belief that it consists of a bag of isolated tricks, a number … One reason why Combinatorics has been slow to become accepted as part of mainstream Mathematics is the common belief that it consists of a bag of isolated tricks, a number of areas: combinatorial number theory (partitions, integer sequences), combinatorial set theory, Ramsey theory, partially ordered sets, lattices (in both the poset and number-theoretic senses), error-correcting codes, combinatorial designs (latin squares and rectangles, projective and affine geometries, Steiner systems, Kirk-man’s schoolgirls problem), combinatorial games, enumerative combinatorics (recurrence relations, generating functions), 0–1 matrices, graph theory (including tournaments, topological properties, coloring problems), combinatorial geometry, packing fc covering (in number-theoretic, set-theoretic, graph-theoretic or geometric contexts) with little or no connexion between them. We shall see that they have numerous threads weaving them together into a beautifully patterned tapestry.
In a Steiner triple system of order v, STS(v), a set of three lines inter­ secting pairwise in three distinct points is called a triangle. A set of lines containing … In a Steiner triple system of order v, STS(v), a set of three lines inter­ secting pairwise in three distinct points is called a triangle. A set of lines containing no triangle is called triangle-free. The minimum number of triangle-free sets required to partition the lines of a Steiner triple system S, is called the triangle chromatic index of S. We prove that for all ad­ missible v, there exists an STS(v) with triangle chromatic index at most 8V3v. In addition, by showing that the projective geometry PG( n, 3) may be partitioned into O( 6 n / 5 ) caps, we prove that the STS( v) formed from the points and lines of the affine geometry AG(n, 3) has triangle chromatic index at most Av s , where s = loge 6/(3 loge 5) ~ 0.326186, and A is a constant. We also determine the values of the index for STS( v) with v ::; 13.
A Sidon set is a subset of an Abelian group with the property that each sum of two distinct elements is distinct. We construct a small maximal Sidon set of … A Sidon set is a subset of an Abelian group with the property that each sum of two distinct elements is distinct. We construct a small maximal Sidon set of size $O((n \cdot 2^n)^{1/3})$ in the group $\mathbb{Z}_2^n$, generalizing a result of Ruzsa concerning maximal Sidon sets in the integers.
It is easily shown that every digraph with m edges has a directed cut of size at least m-4, and that 1-4 cannot be replaced by any larger constant. We … It is easily shown that every digraph with m edges has a directed cut of size at least m-4, and that 1-4 cannot be replaced by any larger constant. We investigate the size of the largest directed cut in acyclic digraphs, and prove a number of related results concerning cuts in digraphs and acyclic digraphs. © 2006 Wiley Periodicals, Inc. J Graph Theory 55: 1–13, 2007
The essential theme of this article is the exploitation of known configurations in projective planes in order to construct pairwise balanced designs. Among the results shown are (q2 + 1)/2 … The essential theme of this article is the exploitation of known configurations in projective planes in order to construct pairwise balanced designs. Among the results shown are (q2 + 1)/2 ∈ B((q + 1)/2, 2) for all odd prime powers q; the resolution of 31 of the Mullin and Stinson's open cases in the spectrum of B(P7, 1), where P7 is odd prime powers ≥ 7; some constructions showing the inessential nature of values in E, where E are PBD generating sets containing values equal to 1 mod(a) for 5 ≤ a ≤ 7; some constructions with block sizes being prime powers ≥ 8, yielding 7 MOLS of order 158 and 9 MOLS of order 254; and some designs on 28, 38, 42, 56, 63, 68, 72, and 156 points with interesting block sizes. © 1999 John Wiley & Sons, Inc. J Combin Designs 7: 341–374, 1999
&lt;p style='text-indent:20px;'&gt;In this paper we construct different families of orbit codes in the vector spaces of the symmetric bilinear forms, quadratic forms and Hermitian forms on an &lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$ n … &lt;p style='text-indent:20px;'&gt;In this paper we construct different families of orbit codes in the vector spaces of the symmetric bilinear forms, quadratic forms and Hermitian forms on an &lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$ n $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;-dimensional vector space over the finite field &lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}$ {\mathbb F_{q}} $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;. All these codes admit the general linear group &lt;inline-formula&gt;&lt;tex-math id="M3"&gt;\begin{document}$ {{{{\rm{GL}}}}}(n,q) $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; as a transitive automorphism group.&lt;/p&gt;
A Sidon set is a subset of an Abelian group with the property that each sum of two distinct elements is distinct. We construct a small maximal Sidon set of … A Sidon set is a subset of an Abelian group with the property that each sum of two distinct elements is distinct. We construct a small maximal Sidon set of size $O((n \cdot 2^n)^{1/3})$ in the group ${\mathbb{Z}}_2^n$, generalizing a result of Ruzsa concerning maximal Sidon sets in the integers.