1. Flatness, convexity and notions of freeness in combinatorial geometries

   • K. L. Holland

   Pages: 1 - 21

2. Relativized relation algebras

   • M. Marx

   Pages: 23 - 45

3. The preservation of Sahlqvist equations in completions of Boolean algebras with operators

   • S. Givant
   • Y. Venema

   Pages: 47 - 84

4. On isotone maps on a countable lattice

   • G. Grätzer
   • A. Hajnal

   Pages: 85 - 86