Below is the ascii version of the abstract for 14-34. The html version should be ready soon.

Pavel Exner and Ondrej Turek
Spectrum of a dilated honeycomb network
(507K, pdf)

ABSTRACT.  We analyze spectrum of Laplacian supported by a periodic honeycomb lattice with generally unequal edge lengths and a $\delta$ type coupling in the vertices. Such a quantum graph has nonempty point spectrum with compactly supported eigenfunctions provided all the edge lengths are commensurate. We derive conditions determining the continuous spectral component and show that existence of gaps may depend on number-theoretic properties of edge lengths ratios. The case when two of the three lengths coincide is discussed in detail.