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arXiv · 2410.11930

Semi-boolean and Yosida $\ell$-groups, Martinez and Yosida frames, and the $G+B$ construction

Papiya Bhattacharjee·Anthony W. Hager·Warren Wm. McGovern·Brian Wynne
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Abstract

The class of semi-boolean $\ell$-groups was introduced in 1968 by A. Bigard. These are the $\ell$-groups $G$ in which the principal convex $\ell$-subgroup $G(a)$ generated by any $a \in G$ is equal to the polar $a^{\perp \perp}$. Examples include all hyperarchimedean $\ell$-groups and all existentially closed abelian $\ell$-groups. Ordered by inclusion, the set of convex $\ell$-subgroups of a semi-boolean $\ell$-group is a \Mart frame (an algebraic frame with FIP in which every element is a $d$-element). Related are the Yosida $\ell$-groups, i.e., the $\ell$-groups whose frame of convex $\ell$-subgroups is a Yosida frame (an algebraic frame with FIP in which every compact element is a meet of maximal elements). Applying results on \Mart frames and Yosida frames, we obtain new characterizations of the semi-boolean and Yosida $\ell$-groups, show that the former constitute a radical class and the latter do not, and present new examples with special properties. To build some of our examples, we introduce the $G+B$ construction for $\ell$-groups, an adaptation of the $A+B$ construction from commutative algebra.

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Papiya Bhattacharjee, Anthony W. Hager, Warren Wm. McGovern, Brian Wynne. 2026-01-09. Semi-boolean and Yosida $\ell$-groups, Martinez and Yosida frames, and the $G+B$ construction. https://arxiv.org/abs/2410.11930

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