  The multifractal formalism for measures in its original formulation is
checked for special classes of measures such as doubling, self-similar, and
Gibbs-like ones. Out of these classes, suitable conditions should be taken into
account to prove the validity of the multifractal formalism. In the present
work, a large class of measures satisfying a weak condition known as quasi
Ahlfors is considered in the framework of mixed multifractal analysis. A joint
multifractal analysis of finitely many quasi Ahlfors probability measures is
developed. Mixed variants of multifractal generalizations of Hausdorff and
packing measures, and corresponding dimensions are introduced. By applying
convexity arguments, some properties of these measures and dimensions are
established. Finally, an associated multifractal formalism is introduced and
proved to hold for the class of quasi Ahlfors measures.
