A.V.Chagrov

All Tabular Generally Post-Complete Extensions of  K4 Have Interpolation Property

We prove that if a modal logic L has the interpolation property and contains the formula pЩ□pЩ...□ⁿp ® □ⁿ⁺¹p, for some n О w, then any tabular generally Post-complete extension of L has the interpolation property too.