Some new bounds and values for van der Waerden-like numbers

Numbers similar to those of van der Waerden are studied. We consider increasing sequences of positive integers {x ₁,x ₂,...,x _n } that either form an arithmetic progression or for which there exists a polynomialf with integer coefficients and degree exactlyn – 2, andx _j+1 =f(x _j ). We denote byq(n, k) the least positive integer such that if {1, 2,...,q(n, k)} is partitioned intok classes, then some class must contain a sequence of the type just described. Upper bounds are obtained forq(n, 3), q(n, 4), q(3, k), andq(4, k). A table of several values is also given.     

Remarks on a sine polynomial

Let n ≥ 0 be an integer. Then we have for ${x\in(0,\pi)}Let n ≥ 0 be an integer. Then we have for x ? (0,p){x\in(0,\pi)} :

?k=0n (( 2n+1) || (n-k ))\fracsin((2k+1)x)2k+1 ￡ \frac8n  n!(2n+1)!!.\sum_{k=0}^n { 2n+1 \choose n-k }\frac{\sin((2k+1)x)}{2k+1}\leq\frac{8^n \, n!}{(2n+1)!!}.      3. On newforms for Kohnen plus spaces      Masaru Ueda  Shunsuke Yamana 《Mathematische Zeitschrift》2010,264(1):1-13 In this article, we investigate the plus space of level N, where 4?1 N is a square-free (not necessarily odd) integer. This is a generalization of Kohnen’s work. We define a Hecke isomorphism ${\wp_k}In this article, we investigate the plus space of level N, where 4−1 N is a square-free (not necessarily odd) integer. This is a generalization of Kohnen’s work. We define a Hecke isomorphism ?k{\wp_k} of M k+1/2(4M) onto Mk+1/2+(8M){M_{k+1/2}^+(8M)} for any odd positive integer M. The methods of the proof of the newform theory are this isomorphism, Waldspurger’s theorem, and the dimension identity.      4. Orthogonal designs II      Anthony V. Geramita  Jennifer Seberry Wallis 《Aequationes Mathematicae》1975,13(3):299-313 Orthogonal designs are a natural generalization of the Baumert-Hall arrays which have been used to construct Hadamard matrices. We continue our investigation of these designs and show that orthogonal designs of type (1,k) and ordern exist for everyk < n whenn = 2 t+2?3 andn = 2 t+2?5 (wheret is a positive integer). We also find orthogonal designs that exist in every order 2n and others that exist in every order 4n. Coupled with some results of earlier work, this means that theweighing matrix conjecture ‘For every ordern ≡ 0 (mod 4) there is, for eachk ?n, a square {0, 1, ? 1} matrixW = W(n, k) satisfyingWW t =kIn’ is resolved in the affirmative for all ordersn = 2t+1?3,n = 2t+1?5 (t a positive integer). The fact that the matrices we find are skew-symmetric for allk < n whenn ≡ 0 (mod 8) and because of other considerations we pose three other conjectures about weighing matrices having additional structure and resolve these conjectures affirmatively in a few cases. In an appendix we give a table of the known results for orders ? 64.      5. On Bachet's diophantine equationx 3=y 2=k      Ulrich Felgner 《Monatshefte für Mathematik》1984,98(3):185-191 Using Eisenstein's law of cubic reciprocity we investigate cases in whichx 3=y 2+k is unsolvable in the ring of rational integers In particular we show, that for all primesp ± 1 (mod 9),p3, the equationx 3=y 2+3p(p±9) has no solutions in .      6. Sums and differences of four kth powers      Oscar Marmon 《Monatshefte für Mathematik》2011,53(9):55-74 We prove an upper bound for the number of representations of a positive integer N as the sum of four kth powers of integers of size at most B, using a new version of the determinant method developed by Heath-Brown, along with recent results by Salberger on the density of integral points on affine surfaces. More generally we consider representations by any integral diagonal form. The upper bound has the form ON(Bc/?k){O_{N}(B^{c/\sqrt{k}})}, whereas earlier versions of the determinant method would produce an exponent for B of order k −1/3 (uniformly in N) in this case. Furthermore, we prove that the number of representations of a positive integer N as a sum of four kth powers of non-negative integers is at most Oe(N1/k+2/k3/2+e){O_{\varepsilon}(N^{1/k+2/k^{3/2}+\varepsilon})} for k ≥ 3, improving upon bounds by Wisdom.      7. On the existence of minimum cubature formulas for Gaussian measure on ?2 of degree t supported by [\frac{t}{4}]+1 circles      Eiichi Bannai  Etsuko Bannai  Masatake Hirao  Masanori Sawa 《Journal of Algebraic Combinatorics》2012,35(1):109-119 In this paper we prove that there exists no minimum cubature formula of degree 4k and 4k+2 for Gaussian measure on ℝ2 supported by k+1 circles for any positive integer k, except for two formulas of degree 4.      8. Diophantine方程(a-1)x~2+f(a)=4a~n的一点注记      乐茂华 《数学学报》2011,54(1):111-114 设a是大于1的正整数,f(a)是a的非负整系数多项式,f(1)=2rp+4,其中r是大于1的正整数,p=2~l-1是Mersenne素数.本文讨论了方程(a-1)x~2+f(a)=4a~n的正整数解(x,n)的有限性,并且证明了:当f(a)=91a+9时,该方程仅当a=5,7和25时分别有解(x,n)=(3,3),(11,3)和(3,4).      9. Minimal 2-Fold Coverings of E d      David Nadler 《Geometriae Dedicata》1997,65(3):305-312 Let N(k, d) be the smallest positive integer such that given any finite collection of open halfspaces which k-fold coversE d , there exists a subcollection of cardinality less than or equal toN(k,d) which k-fold coversE d . A well-known corollary to Helly's theorem proves N(1,d) =d+1. This provides an inductive base from which we show N(k; d) exists for all positive integers k.Our main result is .      10. Generating Uniform Random Vectors      Claudio Asci 《Journal of Theoretical Probability》2001,14(2):333-356 In this paper, we study the rate of convergence of the Markov chain X n+1=AX n +b n mod p, where A is an integer matrix with nonzero integer eigenvalues and {b n } n is a sequence of independent and identically distributed integer vectors. If i±1 for all eigenvalues i of A, then n=O((log p)2) steps are sufficient and n=O(log p) steps are necessary to have X n sampling from a nearly uniform distribution. Conversely, if A has the eigenvalue 1=±1, and i±1 for all i1, n=O(p2) steps are necessary and sufficient.      11. On the existence of wave operators for the Klein-Gordon equation      Klaus-Jürgen Eckardt 《manuscripta mathematica》1976,18(1):43-55 The problem of existence of wave operators for the Klein-Gordon equation ( t 2 –+2+iV1t+V2)u(x,t)=0 (x R n,t R, n3, >0) is studied where V1 and V2 are symmetric operators in L2(R n) and it is shown that conditions similar to those of Veseli-Weidmann (Journal Functional Analysis 17, 61–77 (1974)) for a different class of operators are also sufficient for the Klein-Gordon equation.      12. On the Class-number of the Maximal Real Subfield of a Cyclotomic Field      Azizul Hoque  Helen K. Saikia 《Quaestiones Mathematicae》2016,39(7):889-894 For any square-free positive integer m, let H(m) be the class-number of the field , where ζm is a primitive m-th root of unity. We show that if m = {3(8 g + 5)}2 ? 2 is a square-free integer, where g is a positive integer, then H(4 m) > 1. Similar result holds for a square-free integer m = {3(8 g +7)}2 ?2, where g is a positive integer. We also show that n|H(4 m) for certain positive integers m and n.      13. Integer points on hypersurfaces      Wolfgang M. Schmidt 《Monatshefte für Mathematik》1986,102(1):27-58 Very general hypersurfaces in 4 contain r 2+(4/9) integer points in any ball of radiusr>1. As a consequence, an irreducible algebraic hypersurface in n (wheren4) which is not a cylinder and is of degreed, contains c(d, n)r n–1–(5/9) integer points in a ball of radiusr. This improves on the known boundc(d, n)r n–(3/2).Meinem verehrten Lehrer Professor E. Hlawka zum siebzigsten Geburtstag gewidmetWritten with partial support from NSF-MCS-8211461.      14. Mixed sums of squares and triangular numbers (III)      Byeong-Kweon Oh  Zhi-Wei Sun 《Journal of Number Theory》2009,129(4):964-969 In this paper we confirm a conjecture of Sun which states that each positive integer is a sum of a square, an odd square and a triangular number. Given any positive integer m, we show that p=2m+1 is a prime congruent to 3 modulo 4 if and only if Tm=m(m+1)/2 cannot be expressed as a sum of two odd squares and a triangular number, i.e., p2=x2+8(y2+z2) for no odd integers x,y,z. We also show that a positive integer cannot be written as a sum of an odd square and two triangular numbers if and only if it is of the form 2Tm(m>0) with 2m+1 having no prime divisor congruent to 3 modulo 4.      15. New Hadamard matrices and conference matrices obtained via Mathon's construction      Jennifer Seberry  Albert Leon Whiteman 《Graphs and Combinatorics》1988,4(1):355-377 We give a formulation, via (1, –1) matrices, of Mathon's construction for conference matrices and derive a new family of conference matrices of order 592t+1 + 1,t 0. This family produces a new conference matrix of order 3646 and a new Hadamard matrix of order 7292. In addition we construct new families of Hadamard matrices of orders 692t+1 + 2, 1092t+1 + 2, 8499 t ,t 0;q 2(q + 3) + 2 whereq 3 (mod 4) is a prime power and 1/2(q + 5) is the order of a skew-Hadamard matrix); (q + 1)q 29 t ,t 0 (whereq 7 (mod 8) is a prime power and 1/2(q + 1) is the order of an Hadamard matrix). We also give new constructions for Hadamard matrices of order 49 t 0 and (q + 1)q 2 (whereq 3 (mod 4) is a prime power).This work was supported by grants from ARGS and ACRB.Dedicated to the memory of our esteemed friend Ernst Straus.      16. Variations on Tilings in the Manhattan Metric      Gravier  Sylvain  Mollard  Michel  Payan  Charles 《Geometriae Dedicata》1999,76(3):265-274 We investigate tilings of the integer lattice in the Euclidean n-dimensional space. The tiles considered here are the union of spheres defined by the Manhattan metric. We give a necessary condition for the existence of such a tiling for Z n when n 2. We prove that this condition is sufficient when n=2. Finally, we give some tilings of Z n when n 3.      17. Asymptotic behaviour of the poles of a special generating function for acyclic digraphs      Peter J. Grabner  Bertran Steinsky 《Aequationes Mathematicae》2005,70(3):268-278       18. Sufficient Condition to Resolve Costa's First Conjecture      Najib Mahdou 《代数通讯》2013,41(3):1066-1074 In this work, we give a sufficient condition to resolve Costa's first conjecture for each positive integer n and d with n ≥ 4. Precisely, we show that if there exists a local ring (A, M) such that λ A (M) = n, and if there exists an (n + 2)-presented A-submodule of M m , where m is a positive integer (for instance, if M contains a regular element), then we may construct an example of (n + 4, d)-ring which is neither an (n + 3, d)-ring nor an (n + 4, d ? 1)-ring. Finally, we construct a local ring (B, M) such that λ B (M) = 0 (resp., λ B (M) = 1) and so we exhibit for each positive integer d, an example of a (4, d)-ring (resp., (5, d)-ring) which is neither a (4, d ? 1)-ring (resp., neither a (5, d ? 1)-ring) nor a (2, d′)-ring (resp., nor a (3, d′)-ring) for each positive integer d′.      19. Lexicographic matchings cannot form Hamiltonian cycles      Dwight Duffus  Bill Sands  Robert Woodrow 《Order》1988,5(2):149-161 For any positive integer k let B(k) denote the bipartite graph of k- and k+1-element subsets of a 2k+1-element set with adjacency given by containment. It has been conjectured that for all k, B(k) is Hamiltonian. Any Hamiltonian cycle would be the union of two (perfect) matchings. Here it is shown that for all k>1 no Hamiltonian cycle in B(k) is the union of two lexicographic matchings.Supported by Office of Naval Research Contract N00014-85-K-0769.Supported by NSERC grants 69-3378 and 69-0259.      20. Arithmetic and other properties of certain Delphic semigroups. I      Rollo Davidson 《Probability Theory and Related Fields》1968,10(2):120-145 Summary Some aspects of Delphic semigroups in general — in particular, the idea of an hereditary subsemigroup, which has many uses in connexion with Delphic semigroups — are first treated. After that, attention is directed to the arithmetic of +, the semigroup of positive renewal sequences. In a Delphic semigroup the aboriginal elements are the simples and the members of I 0: a class of simples of + is constructed and the simples are shown to be residual. I 0 is explicitly identified, and this leads to a canonical factorization of +. The properties of division in + are discussed.

On newforms for Kohnen plus spaces

In this article, we investigate the plus space of level N, where 4^?1 N is a square-free (not necessarily odd) integer. This is a generalization of Kohnen’s work. We define a Hecke isomorphism ${\wp_k}In this article, we investigate the plus space of level N, where 4⁻¹ N is a square-free (not necessarily odd) integer. This is a generalization of Kohnen’s work. We define a Hecke isomorphism ?_k{\wp_k} of M _k+1/2(4M) onto M_k+1/2⁺(8M){M_{k+1/2}^+(8M)} for any odd positive integer M. The methods of the proof of the newform theory are this isomorphism, Waldspurger’s theorem, and the dimension identity.     

Orthogonal designs II

Orthogonal designs are a natural generalization of the Baumert-Hall arrays which have been used to construct Hadamard matrices. We continue our investigation of these designs and show that orthogonal designs of type (1,k) and ordern exist for everyk < n whenn = 2 ^t+2?3 andn = 2 ^t+2?5 (wheret is a positive integer). We also find orthogonal designs that exist in every order 2n and others that exist in every order 4n. Coupled with some results of earlier work, this means that theweighing matrix conjecture ‘For every ordern ≡ 0 (mod 4) there is, for eachk ?n, a square {0, 1, ? 1} matrixW = W(n, k) satisfyingWW ^t =kIn’ is resolved in the affirmative for all ordersn = 2^t+1?3,n = 2^t+1?5 (t a positive integer). The fact that the matrices we find are skew-symmetric for allk < n whenn ≡ 0 (mod 8) and because of other considerations we pose three other conjectures about weighing matrices having additional structure and resolve these conjectures affirmatively in a few cases. In an appendix we give a table of the known results for orders ? 64.     

On Bachet's diophantine equationx 3=y 2=k

Using Eisenstein's law of cubic reciprocity we investigate cases in whichx ³=y ²+k is unsolvable in the ring of rational integers In particular we show, that for all primesp ± 1 (mod 9),p3, the equationx ³=y ²+3p(p±9) has no solutions in .     

Sums and differences of four kth powers

We prove an upper bound for the number of representations of a positive integer N as the sum of four kth powers of integers of size at most B, using a new version of the determinant method developed by Heath-Brown, along with recent results by Salberger on the density of integral points on affine surfaces. More generally we consider representations by any integral diagonal form. The upper bound has the form O_N(B^c/?k){O_{N}(B^{c/\sqrt{k}})}, whereas earlier versions of the determinant method would produce an exponent for B of order k ^−1/3 (uniformly in N) in this case. Furthermore, we prove that the number of representations of a positive integer N as a sum of four kth powers of non-negative integers is at most O_e(N^1/k+2/k3/2+e){O_{\varepsilon}(N^{1/k+2/k^{3/2}+\varepsilon})} for k ≥ 3, improving upon bounds by Wisdom.     

On the existence of minimum cubature formulas for Gaussian measure on ?2 of degree t supported by [\frac{t}{4}]+1 circles

In this paper we prove that there exists no minimum cubature formula of degree 4k and 4k+2 for Gaussian measure on ℝ² supported by k+1 circles for any positive integer k, except for two formulas of degree 4.     

Diophantine方程(a-1)x~2+f(a)=4a~n的一点注记

设a是大于1的正整数,f(a)是a的非负整系数多项式,f(1)=2rp+4,其中r是大于1的正整数,p=2~l-1是Mersenne素数.本文讨论了方程(a-1)x~2+f(a)=4a~n的正整数解(x,n)的有限性,并且证明了:当f(a)=91a+9时,该方程仅当a=5,7和25时分别有解(x,n)=(3,3),(11,3)和(3,4).     

Minimal 2-Fold Coverings of E d

Let N(k, d) be the smallest positive integer such that given any finite collection of open halfspaces which k-fold coversE ^d , there exists a subcollection of cardinality less than or equal toN(k,d) which k-fold coversE ^d . A well-known corollary to Helly's theorem proves N(1,d) =d+1. This provides an inductive base from which we show N(k; d) exists for all positive integers k.Our main result is .     

Generating Uniform Random Vectors

In this paper, we study the rate of convergence of the Markov chain X _n+1=AX _n +b _n mod p, where A is an integer matrix with nonzero integer eigenvalues and {b _n } _n is a sequence of independent and identically distributed integer vectors. If _i±1 for all eigenvalues _i of A, then n=O((log p)²) steps are sufficient and n=O(log p) steps are necessary to have X _n sampling from a nearly uniform distribution. Conversely, if A has the eigenvalue ₁=±1, and _i±1 for all i1, n=O(p²) steps are necessary and sufficient.     

On the existence of wave operators for the Klein-Gordon equation

The problem of existence of wave operators for the Klein-Gordon equation ( _t ² –+²+iV_1t+V₂)u(x,t)=0 (x R ⁿ,t R, n3, >0) is studied where V₁ and V₂ are symmetric operators in L₂(R ⁿ) and it is shown that conditions similar to those of Veseli-Weidmann (Journal Functional Analysis 17, 61–77 (1974)) for a different class of operators are also sufficient for the Klein-Gordon equation.     

On the Class-number of the Maximal Real Subfield of a Cyclotomic Field

For any square-free positive integer m, let H(m) be the class-number of the field , where ζ_m is a primitive m-th root of unity. We show that if m = {3(8 g + 5)}² ? 2 is a square-free integer, where g is a positive integer, then H(4 m) > 1. Similar result holds for a square-free integer m = {3(8 g +7)}² ?2, where g is a positive integer. We also show that n|H(4 m) for certain positive integers m and n.     

Integer points on hypersurfaces

Very general hypersurfaces in ⁴ contain r ^2+(4/9) integer points in any ball of radiusr>1. As a consequence, an irreducible algebraic hypersurface in ⁿ (wheren4) which is not a cylinder and is of degreed, contains c(d, n)r ^{n–1–(5/9)} integer points in a ball of radiusr. This improves on the known boundc(d, n)r ^n–(3/2).Meinem verehrten Lehrer Professor E. Hlawka zum siebzigsten Geburtstag gewidmetWritten with partial support from NSF-MCS-8211461.     

Mixed sums of squares and triangular numbers (III)

In this paper we confirm a conjecture of Sun which states that each positive integer is a sum of a square, an odd square and a triangular number. Given any positive integer m, we show that p=2m+1 is a prime congruent to 3 modulo 4 if and only if Tm=m(m+1)/2 cannot be expressed as a sum of two odd squares and a triangular number, i.e., p²=x²+8(y²+z²) for no odd integers x,y,z. We also show that a positive integer cannot be written as a sum of an odd square and two triangular numbers if and only if it is of the form 2Tm(m>0) with 2m+1 having no prime divisor congruent to 3 modulo 4.     

New Hadamard matrices and conference matrices obtained via Mathon's construction

We give a formulation, via (1, –1) matrices, of Mathon's construction for conference matrices and derive a new family of conference matrices of order 59^2t+1 + 1,t 0. This family produces a new conference matrix of order 3646 and a new Hadamard matrix of order 7292. In addition we construct new families of Hadamard matrices of orders 69^2t+1 + 2, 109^2t+1 + 2, 8499 ^t ,t 0;q ²(q + 3) + 2 whereq 3 (mod 4) is a prime power and 1/2(q + 5) is the order of a skew-Hadamard matrix); (q + 1)q ²9 ^t ,t 0 (whereq 7 (mod 8) is a prime power and 1/2(q + 1) is the order of an Hadamard matrix). We also give new constructions for Hadamard matrices of order 49 ^t 0 and (q + 1)q ² (whereq 3 (mod 4) is a prime power).This work was supported by grants from ARGS and ACRB.Dedicated to the memory of our esteemed friend Ernst Straus.     

Variations on Tilings in the Manhattan Metric

We investigate tilings of the integer lattice in the Euclidean n-dimensional space. The tiles considered here are the union of spheres defined by the Manhattan metric. We give a necessary condition for the existence of such a tiling for Z ⁿ when n 2. We prove that this condition is sufficient when n=2. Finally, we give some tilings of Z ⁿ when n 3.     

Sufficient Condition to Resolve Costa's First Conjecture

In this work, we give a sufficient condition to resolve Costa's first conjecture for each positive integer n and d with n ≥ 4. Precisely, we show that if there exists a local ring (A, M) such that λ _A (M) = n, and if there exists an (n + 2)-presented A-submodule of M ^m , where m is a positive integer (for instance, if M contains a regular element), then we may construct an example of (n + 4, d)-ring which is neither an (n + 3, d)-ring nor an (n + 4, d ? 1)-ring. Finally, we construct a local ring (B, M) such that λ _B (M) = 0 (resp., λ _B (M) = 1) and so we exhibit for each positive integer d, an example of a (4, d)-ring (resp., (5, d)-ring) which is neither a (4, d ? 1)-ring (resp., neither a (5, d ? 1)-ring) nor a (2, d′)-ring (resp., nor a (3, d′)-ring) for each positive integer d′.     

Lexicographic matchings cannot form Hamiltonian cycles

For any positive integer k let B(k) denote the bipartite graph of k- and k+1-element subsets of a 2k+1-element set with adjacency given by containment. It has been conjectured that for all k, B(k) is Hamiltonian. Any Hamiltonian cycle would be the union of two (perfect) matchings. Here it is shown that for all k>1 no Hamiltonian cycle in B(k) is the union of two lexicographic matchings.Supported by Office of Naval Research Contract N00014-85-K-0769.Supported by NSERC grants 69-3378 and 69-0259.     

Arithmetic and other properties of certain Delphic semigroups. I

Summary Some aspects of Delphic semigroups in general — in particular, the idea of an hereditary subsemigroup, which has many uses in connexion with Delphic semigroups — are first treated. After that, attention is directed to the arithmetic of ⁺, the semigroup of positive renewal sequences. In a Delphic semigroup the aboriginal elements are the simples and the members of I ₀: a class of simples of ⁺ is constructed and the simples are shown to be residual. I ₀ is explicitly identified, and this leads to a canonical factorization of ⁺. The properties of division in ⁺ are discussed.