In this paper we develop an algebraic framework in which several classes of two-valued \nstates over orthomodular lattices may be equationally characterized. The class of two-valued \nstates and the subclass of Jauch–Piron two-valued states are among the classes which we study
A Boolean orthoposet is the orthoposet P fulfilling the following condition: if a ^ b = 0 then a ? b. Boolean orthoposets enjoy some properties of Boolean algebras but, in some sense, they are far away of them (3, 4, 8). An important notion in quantum logic theory is the notion of Jauch-Piron state (2, 5, 6, 7). In this paper, we show connections between Boolean orthoposets and orthoposets with a proper number of Jauch-Piron states: We demonstrate that an orthoposet with enough two-valued Jauch-Piron states is Boolean and, on the other hand, we give several examples of Boolean orthoposets without any two- valued Jauch-Piron state.
In the logico-algebraic foundation of quantum mechanics one often deals with the orthomodular lattices (OML) which enjoy state-separating properties of noncompatible pairs (see e.g. [18], [9] and [15]). These properties usually guarantee reasonable “richness” of the state space—an assumption needed in developing the theory of quantum logics. In this note we consider these classes of OMLs from the universal algebra standpoint, showing, as the main result, that these classes form quasivarieties. We also illustrate by examples that these classes may (and need not) be varieties. The results supplement the research carried on in [1], [3], [4], [5], [6], [11], [12], [13] and [16].
We show in this note that if [Formula: see text] is a Boolean subalgebra of the lattice quantum logic [Formula: see text], then each state on [Formula: see text] can be extended over [Formula: see text] as a Jauch–Piron state provided [Formula: see text] is Jauch–Piron unital with respect to [Formula: see text] (i.e. for each nonzero [Formula: see text], there is a Jauch–Piron state [Formula: see text] on [Formula: see text] such that [Formula: see text]). We then discuss this result for the case of [Formula: see text] being the Hilbert space logic [Formula: see text] and [Formula: see text] being a set-representable logic.
We present several known and one new description of orthomodular structures (orthomodular lattices, orthomodular posets and orthoalgebras). Originally, orthomodular structures were viewed as pasted families of Boolean algebras. Here we introduce semipasted families of Boolean algebras as an alternative description which is not as detailed, but substantially simplex. Semipasted families of Boolean algebras correspond to orthomodular structures in such a way that states and evaluation functionals are preserved. As semipasted families of Boolean algebras are quite general, they allow an easy construction of orthomodular structures with given state space properties. Based on this technique, we give a simplified proof of Shultz's Theorem on characterization of spaces of finitely additive states on orthomodular lattices. We also put some other results into the new context. We give a detailed exposition of the construction techniques as a tool for further applications, especially for finding counterexamples to questions about states on orthomodular structures.