Gelfand-Naimark-Stone duality for normal spaces and insertion theorems

Gelfand-Naimark-Stone duality provides an algebraic counterpart of compact Hausdorff spaces in the form of uniformly complete bounded archimedean $\ell$-algebras. In [4] we extended this duality to completely regular spaces. In this article we use this extension to characterize normal, Lind\"{e}lof, and locally compact Hausdorff spaces. Our approach gives a different perspective on the classical theorems of Kat\v{e}tov-Tong and Stone-Weierstrass.