Algebraic orthogonality and commuting projections in operator algebras

We describe absolutely ordered $p$-normed spaces, for $1 \le p \le \infty$ which presents a model for "non-commutative" vector lattices and includes order theoretic orthogonality. To demonstrate its relevance, we introduce the notion of {\it absolute compatibility} among positive elements in absolute order unit spaces and relate it to symmetrized product in the case of a C$^{\ast}$-algebra. In the latter case, whenever one of the elements is a projection, the elements are absolutely compatible if and only if they commute. We develop an order theoretic prototype of the results. For this purpose, we introduce the notion of {\it order projections} and extend the results related to projections in a unital C$^{\ast}$-algebra to order projections in an absolute order unit space. As an application, we describe spectral decomposition theory for elements of an absolute order unit space.Comment: 2

A generalization of spin factors

Using the technique of adjoining an order unit to a normed linear space, we have characterized strictly convex spaces among normed linear spaces and Hilbert spaces among strictly convex Banach spaces, respectively. This leads to a generalization of spin factors and provides a new class of absolute order unit spaces

CM-ideals and L1-matricial split faces

We discuss the order-theoretic properties of CM-ideals in matricially order smooth∞-normed spaces. We study the relation between CM-ideals and CL-summands in the matrix duality setup. We introduce the notion of L1-matricial split faces in an L1-matricially normed space and characterize CM-ideals in a matricially order smooth∞-normed space Vin terms of the L1-matricial split face of the L1-matrix convex set{Qn(V)}