@unpublished{2d-ss-sing-classification,
    author = {Antonio Cocan and Maarten V. de Hoop and Joonas Ilmavirta and Pieti Kirkkopelto and Antti Kykkänen},
    title = {{Classification of singularities of planar slowness surfaces}},
    month = jun,
    year = 2026,
    arxiv = {2606.28527},
    url = {http://users.jyu.fi/~jojapeil/pub/2d-ss-sing-classification.pdf},
    abstract = {Slowness surfaces are algebraic varieties arising from propagation of elastic waves. In dimensions 2, we completely classify the types of singularities slowness surfaces can have. The two types of possible singularities are a transversal self-intersection and a tangential singularity produced by a concentric circle and ellipse that are tangent to each other. To interpret these results analytically, in the case that the slowness surface has transversal self-intersections, we show that the principal symbol of the elastic wave operator is locally smoothly diagonalizable.}
}