A spectral construction of a treed domain that is not going-down
Let be a Hilbert algebra. The monoid of all unary operations on generated by operations , which is actually an upper semilattice w.r.t. the pointwise ordering, is called the adjoint semilattice of . This semilattice is isomorphic to the semilattice of finitely generated filters of , it is subtractive (i.e., dually implicative), and its ideal lattice is isomorphic to the filter lattice of . Moreover, the order dual of the adjoint semilattice is a minimal Brouwerian extension of , and the...
A -labeled -poset is an (at most) countable set, labeled in the set , equipped with partial orders. The collection of all -labeled -posets is naturally equipped with binary product operations and -ary product operations. Moreover, the -ary product operations give rise to
A Σ-labeled n-poset is an (at most) countable set, labeled in the set Σ, equipped with n partial orders. The collection of all Σ-labeled n-posets is naturally equipped with n binary product operations and nω-ary product operations. Moreover, the ω-ary product operations give rise to nω-power operations. We show that those Σ-labeled n-posets that can be generated from the singletons by the binary and ω-ary product operations form the free algebra on Σ in a variety axiomatizable by an infinite collection...