2 problems

Goldblatt–Thomason conjecture for distribution-free modal logics. The classical Goldblatt–Thomason theorem should lift to the sorted modal logic case, yielding a related result for…

Let $p$ be a proposition letter, and let hspace{.2ex}text{% tikz[baseline=-.6ex, rounded corners=.01ex, line width=.12ex] {draw (-.6ex,-.6ex) rectangle (.6ex,.6ex);}}kern.2ex and…