IntroductionIn the last recent years an increasing interest has been devoted to degenerate parabolic equations. Indeed, many problems coming from physics (boundary layer models in [13], models of Kolmogorov type in [7], . . . ), biology (Wright-Fisher models in [50] and Fleming-Viot models in [29]), and economics (Black-MertonScholes equations in [23]) are described by degenerate parabolic equations, whose linear prototype iswith the associated desired boundary conditions, whereIn this paper we concentrate on a special topic related to this field of research, i.e. Carleman estimates for the adjoint problem to (1.1). Indeed, they have so many applications that a large number of papers has been devoted to prove some forms of them and possibly some applications. For example, it is well known that they are a fundamental tool to prove observability inequalities, which lead to global null controllability results for (1.1) also in the non degenerate case: for all T > 0 and for all initial data u 0 ∈ L 2 ((0, T ) × (0, 1)) there is a suitable control h ∈ L 2 ((0, T ) × (0, 1)), supported in a subset ω of [0, 1], such that the solution u of (1.1) satisfies u(T, x) = 0 for all x ∈ [0, 1] (see, for instance, The common point of all the previous papers dealing with degenerate equations, is that the function a degenerates at the boundary of the domain. For example, as a, one can consider the double power functionwhere k and α are positive constants. For related systems of degenerate equations we refer to [1], [2] and [14]. However, the papers cited above deal with a function a that degenerates at the boundary of the spatial domain. To our best knowledge, [51] is the first paper treating the existence of a solution for the Cauchy problem associated to a parabolic equation which degenerates in the interior of the spatial domain, while degenerate parabolic problems modelling biological phenomena and related optimal control problems are later studied in [43] and [9]. Recently, in [32] the authors analyze in detail the degenerate operator A in the space L 2 (0, 1), with or without weight,