S.B. Riesz

The S.B. Riesz theorem is a result in mathematics that deals with how certain functions, called measures, relate to harmonic functions—special functions that satisfy a mean-value property and are smooth inside a domain. It states that if a measure is supported outside a given region, then its associated integral cannot negatively affect harmonic functions inside that region. In simpler terms, it assures that measures located outside a domain don't interfere with the harmonic behavior inside, helping mathematicians understand how boundary and external influences relate to internal properties of functions.