Robinson, DerekSikora, Adam2015-12-070025-5874http://hdl.handle.net/1885/25726We analyse degenerate, second-order, elliptic operators H in divergence form on L 2(R n × R m ). We assume the coefficients are real symmetric and a 1 H δ ≥ H ≥ a2 Hδ for some a1, a2 > 0 where Hδ=-∇x1·(c δ1,δ′1 (x1) ∇x1) - cδ2,δ′2 (x1200810.1007/s00209-007-0284-32015-12-07