A linear hypergraph is a hypergraph $H=(V,E)$ such that
- for $e\in E$ we have $|e|\geq 2$, and
- if $e\neq e_1\in E$, then $|e\cap e_1| \leq 1$.
AAn self-coloringinjective edge choice function of a linear hypergraph is aan injective map $f:E\to V$ such that:
- for all $e\in E$ we have $f(e)\in e$, and
- if $e\neq e_1\in E$ with $e\cap e_1\neq \emptyset$, then $f(e)\neq f(e_1)$.
for all $e\in E$ we have $f(e)\in e$.
One can verify that the hypergraph $H=(V,E)$ where $V = \{0,1,2,3\}$ andObviously, if $E = [V]^2 = \{\{a,b\}:a\neq b\in V\}$ has no self-coloring$|E|>|V|$ there cannot be such a function.
Question. If $H=(V,E)$ is a linear hypergraph with $V$ finite and $|e|\geq 3$ for all $e\in E$, does $H$ necessarily have a self-coloringan injective edge choice function?