The Riesz-Kantorovich formulas for $\mathbb{L}$-vector lattices
Tomas Chamberlain, Marten Wortel
TL;DR
The paper develops an $\mathbb{L}$-valued version of the Riesz-Kantorovich formulas for order-bounded $\mathbb{L}$-module homomorphisms, extending classical vector-lattice results to the setting of $\mathbb{L}$-vector lattices. It introduces an $\mathbb{L}$-valued extension lemma, analyzes Archimedean properties, and proves that the space of order-bounded operators $\mathcal{L}_b(X,Y)$ forms an $\mathbb{L}$-vector lattice equal to the regular operators $\mathcal{L}_r(X,Y)$, with explicit lattice operations given by pointwise sup/inf decompositions: $(S\vee T)(x)=\sup\{S(y)+T(x-y): y\in[0,x]\}$ and $(S\wedge T)(x)=\inf\{S(y)+T(x-y): y\in[0,x]\}$, along with $S^+(x)$, $S^-(x)$, and $|S|(x)$ formulas. The results establish Dedekind completeness of $\mathcal{L}_b(X,Y)$ and yield that the dual $X^\sim$ is a Dedekind-complete $\mathbb{L}$-vector lattice. This broadens the functional-analytic toolkit for $\mathbb{L}$-modules and $\mathbb{L}$-vector lattices, with potential impact on probabilistic and ergodic-theoretic contexts where conditional expectations and $\mathbb{L}$-valued norms arise.
Abstract
Let $\mathbb{L}$ be a Dedekind complete unital $f$-algebra. We prove the Riesz-Kantorovich formulas for order bounded $\mathbb{L}$-module homomorphisms from a directed partially ordered $\mathbb{L}$-module with the Riesz Decomposition Property into a Dedekind complete $\mathbb{L}$-vector lattice satisfying an additional mild condition.
