To untangle a geometric graph means to move some of the vertices so that the resulting geometric graph has no crossings. Pach and Tardos (Discrete Comput. Geom. 28(4): 585–592, 2002) asked if every n-vertex geometric planar ...

The spectral excess theorem provides a quasi-spectral characterization for a (regular) graph Γ with d+1 distinct eigenvalues to be distance-regular graph, in terms of the excess (number of vertices at distance d) of each ...

This paper shows how, using elementary Distance Geometry, a closure polynomial of degree 8 for the Dixon linkage can be derived without any trigonometric substitution, variable elimination, or artifice to collapse mirror ...

A general framework is presented for automatig the discovery of loop invariants for imperative programs. Theoretical results about the correctness and completeness of the proposed method are given. More importantly, it is ...

In this work, we concentrate on determining explicit expressions, via suitable orthogonal polynomials on the line, for the Green function associated with any regular boundary value problem on a weighted path, whose weights ...

This paper deals with data-aided channel estimation in systems using OFDM modulation. We formulate a pilot symbol-based channel estimator and compare it with the pilot-tone one proposed in [1]. Although this paper focuses ...

We study certain language classes located between P and N P that are defined by polynomial time machines with a bounded amount of nondeterminism. We observe that these classes have complete problems and find a characterization ...