Marcelo Campos

Instituto Nacional de Matemática Pura e Aplicada · Pure Mathematics

For every $k \geq 3$, we determine the order of growth, up to polylogarithmic factors, of the number of orientations of the binomial random graph containing no directed cycle of length $k$. This solves a conjecture of Kohayakawa, Morris and the last two authors.

We determine the order of growth, up to polylogarithmic factors, of the number of orientations of the binomial random graph G(n, p) containing no directed cycle of length k for every k⩾3. This solves a conjecture of Kohayakawa, Morris and the last two authors.

In this paper we determine the number and typical structure of sets of integers with bounded doubling. In particular, improving recent results of Green and Morris, and of Mazur, we show that the following holds for every fixed $\lambda> 2$ and every $k \geqslant (\log n)^4$: if $\omega \rightarrow \infty $ as $n \rightarrow \infty $ (arbitrarily sl...

In this paper we determine the number and typical structure of sets of integers with bounded doubling. In particular, improving recent results of Green and Morris, and of Mazur, we show that the following holds for every fixed $\lambda > 2$ and every $k \geqslant (\log n)^4$: if $\omega \to \infty$ as $n \to \infty$ (arbitrarily slowly), then almos...

A well-known conjecture states that a random symmetric $n \times n$ matrix with entries in $\{-1,1\}$ is singular with probability $\Theta\big( n^2 2^{-n} \big)$. In this paper we prove that the probability of this event is at most $\exp\big( - \Omega( \sqrt{n} ) \big)$, improving the best known bound of $\exp\big( - \Omega( n^{1/4} \sqrt{\log n} )...

We study the number of $s$-element subsets $J$ of a given abelian group $G$, such that $|J+J|\leq K|J|$. Proving a conjecture of Alon, Balogh, Morris and Samotij, and improving a result of Green and Morris, who proved the conjecture for $K$ fixed, we provide an upper bound on the number of such sets which is tight up to a factor of $2^{o(s)},$ when...