An idea for quantization by means of geometric observables is explained, which is a kind of the sheaf theoretical methods. First the formulation of differential geometry by using the structure sheaf is explained. The point of view to get interesting noncommutative observable algebras of geometric fields is introduced. The idea is to deform the algebra $C^{\infty }(M,ℝ)$ by suitable interaction structures. As an example of such structures the Poisson-structure is mentioned and this leads naturally to deformation...

The paper deals with locally connected continua $X$ in the Euclidean plane. Theorem 1 asserts that there exists a simple closed curve in $X$ that separates two given points $x$, $y$ of $X$ if there is a subset $L$ of $X$ (a point or an arc) with this property. In Theorem 2 the two points $x$, $y$ are replaced by two closed and connected disjoint subsets $A$, $B$. Again – under some additional preconditions – the existence of a simple closed curve disconnecting $A$ and $B$ is stated.