Abstract: Let $u$ be a $\delta $-subharmonic function with associated measure $\mu $, and let $v$ be a superharmonic function with associated measure $\nu $, on an open set $E$. For any closed ball $B(x,r)$, of centre $x$ and radius $r$, contained in $E$, let $\MM (u,x,r)$ denote the mean value of $u$ over the surface of the ball. We prove that the upper and lower limits as $s,t\to 0$ with $0<s<t$ of the quotient $(\MM (u,x,s)-\MM (u,x,t))/(\MM (v,x,s)-\MM (v,x,t))$, lie between the upper and lower limits as $r\to 0+$ of the quotient $\mu (B(x,r))/\nu (B(x,r))$. This enables us to use some well-known measure-theoretic results to prove new variants and generalizations of several theorems about $\delta $-subharmonic functions.
Keywords: superharmonic, $\delta$-subharmonic function, Riesz measure, spherical mean values
Classification (MSC2000): 31B05
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