Semigroups Underlying First-order Logic

Boolean, relation-induced, and other operations for dealing with first-order definability Uniform relations between sequences Diagonal relations Uniform diagonal relations and some kinds of bisections or bisectable relations Presentation of ${/mathbf S}_q$, ${/mathbf S}_p$ and related structures Presentation of ${/mathbf S}_{pq}$, ${/mathbf S}_{pe}$ and related structures Appendix. Presentation of ${/mathbf S}_{pqe}$ and related structures Bibliography Index of symbols Index of phrases and subjects List of relations involved in presentations Synopsis of presentations.