4 problems

A planar linear normal $\lambda$-term is a linear normal $\lambda$-term whose syntactic diagram is planar; call it 3-connected when its syntactic diagram is 3-connected. For…

Continuous-semantics conjecture. All the effective models living in the continuous semantics have non-r.e. equational theories.

Effective graph-model conjecture. All the effective graph models have non-r.e. equational theories.

Minimum-theory conjecture. The minimum equational graph theory is non-r.e.