%0 Journal Article %T Discreteness of Transmission Eigenvalues for Higher-Order Main Terms and Perturbations %A Andoni Garc¨Şa %A Esa V. Vesalainen %A Miren Zubeldia %J Mathematics %D 2015 %I arXiv %X In this paper we extend Sylvester's approach via upper triangular compact operators to establish the discreteness of transmission eigenvalues for higher-order main terms and higher-order perturbations. The coefficients of the perturbations must be sufficiently smooth and the coefficients of the higher-order terms of the perturbation must vanish in a neighbourhood of the boundary of the underlying domain. The zeroeth order term must satisfy a suitable coercivity condition in a neighbourhood of the boundary. %U http://arxiv.org/abs/1512.05580v1