2 citations · 2 across the 1 of their papers we have counts for
5 papers
A Li-type criterion for zero-free half-planes of Riemann's zeta function
Pedro Freitas
We define a sequence of real functions which coincide with Li's coefficients at one and which allow us to extend Li's criterion for the Riemann Hypothesis to yield a necessary and…
A Heawood-type result for the algebraic connectivity of graphs on surfaces
Pedro Freitas
We prove that the algebraic connectivity a(G) of a graph embedded on a nonplanar surface satisfies a Heawood-type result. More precisely, it is shown that the algebraic connectivit…
Characterization of harmonic and subharmonic functions via mean-value properties
Pedro Freitas, Joao Palhoto Matos
We give a characterization of harmonic and subharmonic functions in terms of their mean values in balls and on spheres. This includes the converse of an inequality of Beardon's for…
Closed nodal lines and interior hot spots of the second eigenfunction of the Laplacian on surfaces
P. Freitas
We build a one-parameter family of S^{1}-invariant metrics on the unit disc with fixed total area for which the second eigenvalue of the Laplace operator in the case of both Neuman…
On the invariant spectrum of -invariant metrics on
Miguel Abreu, Pedro Freitas
A theorem of J. Hersch (1970) states that for any smooth metric on , with total area equal to , the first nonzero eigenvalue of the Laplace operator acting on functions is…