Let (X1,Σ1,μ1) and (X2,Σ2,μ2) be two measure spaces, and let Σ1⊗Σ2 be the σ-algebra generated by sets of the form B1×B2 for B1∈Σ1, B2∈Σ2. A product measure μ1×μ2 is a measure on the measurable space (X1×X2,Σ1⊗Σ2) such that (μ1×μ2)(B1×B2)=μ1(B1)μ2(B2) for all B1∈Σ1, B2∈Σ2.
Wikidata ID: Q1572094