2 problems

Let $C_1$ and $C_2$ be extremal classes with $C_1\subseteq C_2$ and $|C_2\setminus C_1|\geq 2$. Intermediate extremal-class conjecture. There exists an extremal class $C$ such that…

Let $C$ be an extremal class. A concept $c\in C$ is a corner of $C$ if $C\setminus\{c\}$ is extremal. Corner-peeling conjecture. Every nonempty extremal class $C$ has at least one…