A general theory of optimal natural dualities is presented, built on the test algebra technique introduced in an earlier paper. Given that a set R of finitary algebraic relations yields a duality on… (More)

L. M/trki and R. P6schel have characterised the endoprimal distributive lattices as those which are not relatively complemented. The theory of natural dualities implies that any finite algebra A on… (More)

STUDY DESIGN
A database for estimated normal spinal motion was derived using a noninvasive, high-resolution, computer-aided system, which tracks the motion of skin markers strategically placed on the… (More)

A topological quasi-variety Q T ∼ ) := IScP + ∼ generated by a finite algebra ∼ with the discrete topology is said to be standard if it admits a canonical axiomatic description. Drawing on the formal… (More)

We characterize the finite graph algebras which are dualizable. Indeed, a finite graph algebra is dualizable if and only if each connected component of the underlying graph is either complete or… (More)

A natural dl:sitty is obtained for each finitely generated variety B,, (n < CG) of distributive p-algebras. 7 he duality for B,, is based on a schizophrenic object: E:, in B,, is the algebra 2” @ 1… (More)

Given an algebra M we may adjoin an isolated zero to form an algebra M∞ satisfying all identities u ≈ v true in M for which u and v contain the same variables. Drawing on the structure theory of P… (More)

Perhaps the most fundamental problem in the theory of natural dualities is the dualisability problem: deciding exactly which finite algebras generate a quasivariety that admits a natural duality. One… (More)

We prove the claim made in the title of the paper. It is to be expected that different generating algebras D ndM for a quasi-variety will lead to different natural dualities. Indeed, this is the… (More)