Let (X,Σ,μ)(X,\Sigma,\mu)(X,Σ,μ) be a measure space. A property PPP holds almost everywhere in XXX if there exists a set N∈ΣN \in \SigmaN∈Σ such that μ(N)=0\mu(N) = 0μ(N)=0 and PPP is true for all x∈X∖Nx \in X\setminus Nx∈X∖N.
Wikidata ID: Q1139334