Modelled distributions of Triebel–Lizorkin type

Abstract

In order to provide a local description of a regular function in a small neighbourhood of a point $x$, it is sufficient by Taylor's theorem to know the value of the function as well as all of its derivatives up to the required order at the point $x$ itself. In other words, one could say that a regular function is locally modelled by the set of polynomials. The theory of regularity structures due to Hairer generalizes this observation and provides an abstract setup, which in the application of singular SPDE extends the set of polynomials by functionals constructed from, e.g., white noise. In this context, the notion of Taylor polynomials is lifted to the notion of so-called modelled distributions. The celebrated reconstruction theorem, which in turn was inspired by Gubinelli's sewing lemma, is of paramount importance for the theory. It enables to reconstruct a modelled distribution as a true distribution on $R^d$ which is locally approximated by this extended set of models or monomials. In the original work of Hairer, the error is measured based on Holder norms. This was then generalized to the whole scale of Besov spaces by Hairer and Labbe in subsequent papers. It is the aim of this work to adapt the analytic part of the theory of regularity structures to the scale of Triebel-Lizorkin spaces.