Around Pelikán’s conjecture on very odd sequences
نویسندگان
چکیده
Very odd sequences were introduced in 1973 by Pelikán who conjectured that there were none of length ≥ 5. This conjecture was disproved first by MacWilliams and Odlyzko [17] in 1977 and then by two different sets of authors in 1992 [1], 1995 [9]. We give connections with duadic codes, cyclic difference sets, levels (Stufen) of cyclotomic fields, and derive some new asymptotic results on the length of very odd sequences and the number of such sequences of a given length.
منابع مشابه
On Silverman's conjecture for a family of elliptic curves
Let $E$ be an elliptic curve over $Bbb{Q}$ with the given Weierstrass equation $ y^2=x^3+ax+b$. If $D$ is a squarefree integer, then let $E^{(D)}$ denote the $D$-quadratic twist of $E$ that is given by $E^{(D)}: y^2=x^3+aD^2x+bD^3$. Let $E^{(D)}(Bbb{Q})$ be the group of $Bbb{Q}$-rational points of $E^{(D)}$. It is conjectured by J. Silverman that there are infinitely many primes $p$ for which $...
متن کاملSome conjectures on perfect graphs
The complement of a graph G is denoted by G. χ(G) denotes the chromatic number and ω(G) the clique number of G. The cycles of odd length at least five are called odd holes and the complements of odd holes are called odd anti-holes. A graph G is called perfect if, for each induced subgraph G of G, χ(G) = ω(G). Classical examples of perfect graphs consist of bipartite graphs, chordal graphs and c...
متن کاملOdd Collatz Sequence and Binary Representations
Here we investigate the odd numbers in Collatz sequences (sequences arising from the 3n+1 problem). We are especially interested in methods in binary number representations of the numbers in the sequence. In the first section, we show some results for odd Collatz sequences using mostly binary arithmetics. We see how some results become more obvious in binary arithmetic than in usual method of c...
متن کاملBinary m-sequences with three-valued crosscorrelation: A proof of Welch's conjecture
We prove the long-standing conjecture of Welch stating that for odd = 2 + 1, the power function with = 2 + 3 is maximally nonlinear on GF (2 ) or, in other terms, that the crosscorrelation function between a binary maximum-length linear shift register sequences of degree and a decimation of that sequence by 2 + 3 takes on precisely the three values 1 1 2 .
متن کاملBarker sequences of odd length
A Barker sequence is a binary sequence for which all non-trivial aperiodic autocorrelations are at most 1 in magnitude. An old conjecture due to Turyn asserts that there is no Barker sequence of length greater than 13. In 1961, Turyn and Storer gave an elementary, though somewhat complicated, proof that this conjecture holds for odd lengths. We give a new and simpler proof of this result.
متن کامل