To any Nash germ invariant under right composition with a linear action of a finite group, we associate its equivariant zeta functions, inspired from motivic zeta functions, using the equivariant virtual Poincaré series as a motivic measure. We show Denef-Loeser formulae for the equivariant zeta functions and prove that they are invariants for equivariant blow-Nash equivalence via equivariant blow-Nash isomorphisms. Equivariant blow-Nash equivalence between invariant Nash germs is defined as a generalization involving equivariant data of the blow-Nash equivalence.
IntroductionA crucial issue in the study of real analytic germs is the choice of a good equivalence relation by which we can distinguish them. One may think about C r -equivalence, r = 0, 1, . . . , ∞, ω. However, the topological equivalence seems, unlike the complex case, not fine enough : for example, all the germs of the form x 2m +y 2n are topologically equivalent. On the other hand, the C 1 -equivalence has already moduli : consider the Whitney family f t (x, y) = xy(y − x)(y − tx), t > 1, then f t and f t ′ are C 1 -equivalent if and only if t = t ′ . In [15], T.-C. Kuo proposed an equivalence relation for real analytic germs named the blow-analytic equivalence for which, in particular, analytically parametrized family of isolated singularities have a locally finite classification. Roughly speaking, two real analytic germs are said blow-analytically equivalent if they become analytically equivalent after composition with real modifications (e.g., finite successions of blowings-up along smooth centers). With respect to this equivalence relation, Whitney family has only one equivalence class. Slightly stronger versions of blow-analytic equivalence have been proposed so far, by S. Koike and A. Parusiński in [13] and T. Fukui and L. Paunescu in [8] for example. An important feature of blow-analytic equivalence is also that we have invariants for this equivalence relation, like the Fukui invariants ([7]) and the zeta functions ([13]) inspired by the motivic zeta functions of J. Denef and F. Loeser ([5]) using the Euler characteristic with compact supports as a motivic measure.The present paper is interested in the study of Nash germs, that is real analytic germs with semialgebraic graph. In [10], G. Fichou defined an analog adapted to Nash germs of the