Does there exist a harmonic function defined in the unit disk such that
(1) $f(0)=1$
(2) area of $\{z\in\mathbb{D}:\,f(z)>0\}$ is equal to zero?
I tried to use certain representations of harmonic functions, and to relate it to analytic content.
Does there exist a harmonic function defined in the unit disk such that
(1) $f(0)=1$
(2) area of $\{z\in\mathbb{D}:\,f(z)>0\}$ is equal to zero?
I tried to use certain representations of harmonic functions, and to relate it to analytic content.
Since $f$ is continuous and $f(0)=1$ then there exists $r>0$ such that the inequality $x^2 +y^2<r$ implies that $f(x,y)>\frac{1}{2} .$ Hence $$m(\{z\in\mathbb{D}: f(z)>0\} )>\pi r^2 >0,$$ where $m$ denotes the Lebesgue measure.