Locally convex vector lattice
In mathematics, specifically in order theory and functional analysis, a locally convex vector lattice (LCVL) is a topological vector lattice that is also a locally convex space.[1] LCVLs are important in the theory of topological vector lattices.
Lattice semi-norms
[edit ]The Minkowski functional of a convex, absorbing, and solid set is a called a lattice semi-norm. Equivalently, it is a semi-norm {\displaystyle p} such that {\displaystyle |y|\leq |x|} implies {\displaystyle p(y)\leq p(x).} The topology of a locally convex vector lattice is generated by the family of all continuous lattice semi-norms.[1]
Properties
[edit ]Every locally convex vector lattice possesses a neighborhood base at the origin consisting of convex balanced solid absorbing sets.[1]
The strong dual of a locally convex vector lattice {\displaystyle X} is an order complete locally convex vector lattice (under its canonical order) and it is a solid subspace of the order dual of {\displaystyle X}; moreover, if {\displaystyle X} is a barreled space then the continuous dual space of {\displaystyle X} is a band in the order dual of {\displaystyle X} and the strong dual of {\displaystyle X} is a complete locally convex TVS.[1]
If a locally convex vector lattice is barreled then its strong dual space is complete (this is not necessarily true if the space is merely a locally convex barreled space but not a locally convex vector lattice).[1]
If a locally convex vector lattice {\displaystyle X} is semi-reflexive then it is order complete and {\displaystyle X_{b}} (that is, {\displaystyle \left(X,b\left(X,X^{\prime }\right)\right)}) is a complete TVS; moreover, if in addition every positive linear functional on {\displaystyle X} is continuous then {\displaystyle X} is of {\displaystyle X} is of minimal type, the order topology {\displaystyle \tau _{\operatorname {O} }} on {\displaystyle X} is equal to the Mackey topology {\displaystyle \tau \left(X,X^{\prime }\right),} and {\displaystyle \left(X,\tau _{\operatorname {O} }\right)} is reflexive.[1] Every reflexive locally convex vector lattice is order complete and a complete locally convex TVS whose strong dual is a barreled reflexive locally convex TVS that can be identified under the canonical evaluation map with the strong bidual (that is, the strong dual of the strong dual).[1]
If a locally convex vector lattice {\displaystyle X} is an infrabarreled TVS then it can be identified under the evaluation map with a topological vector sublattice of its strong bidual, which is an order complete locally convex vector lattice under its canonical order.[1]
If {\displaystyle X} is a separable metrizable locally convex ordered topological vector space whose positive cone {\displaystyle C} is a complete and total subset of {\displaystyle X,} then the set of quasi-interior points of {\displaystyle C} is dense in {\displaystyle C.}[1]
Theorem[1] —Suppose that {\displaystyle X} is an order complete locally convex vector lattice with topology {\displaystyle \tau } and endow the bidual {\displaystyle X^{\prime \prime }} of {\displaystyle X} with its natural topology (that is, the topology of uniform convergence on equicontinuous subsets of {\displaystyle X^{\prime }}) and canonical order (under which it becomes an order complete locally convex vector lattice). The following are equivalent:
- The evaluation map {\displaystyle X\to X^{\prime \prime }} induces an isomorphism of {\displaystyle X} with an order complete sublattice of {\displaystyle X^{\prime \prime }.}
- For every majorized and directed subset {\displaystyle S} of {\displaystyle X,} the section filter of {\displaystyle S} converges in {\displaystyle (X,\tau )} (in which case it necessarily converges to {\displaystyle \sup S}).
- Every order convergent filter in {\displaystyle X} converges in {\displaystyle (X,\tau )} (in which case it necessarily converges to its order limit).
Corollary[1] —Let {\displaystyle X} be an order complete vector lattice with a regular order. The following are equivalent:
- {\displaystyle X} is of minimal type.
- For every majorized and direct subset {\displaystyle S} of {\displaystyle X,} the section filter of {\displaystyle S} converges in {\displaystyle X} when {\displaystyle X} is endowed with the order topology.
- Every order convergent filter in {\displaystyle X} converges in {\displaystyle X} when {\displaystyle X} is endowed with the order topology.
Moreover, if {\displaystyle X} is of minimal type then the order topology on {\displaystyle X} is the finest locally convex topology on {\displaystyle X} for which every order convergent filter converges.
If {\displaystyle (X,\tau )} is a locally convex vector lattice that is bornological and sequentially complete, then there exists a family of compact spaces {\displaystyle \left(X_{\alpha }\right)_{\alpha \in A}} and a family of {\displaystyle A}-indexed vector lattice embeddings {\displaystyle f_{\alpha }:C_{\mathbb {R} }\left(K_{\alpha }\right)\to X} such that {\displaystyle \tau } is the finest locally convex topology on {\displaystyle X} making each {\displaystyle f_{\alpha }} continuous.[2]
Examples
[edit ]Every Banach lattice, normed lattice, and Fréchet lattice is a locally convex vector lattice.
See also
[edit ]- Banach lattice – Banach space with a compatible structure of a lattice
- Fréchet lattice – Topological vector lattice
- Normed lattice
- Vector lattice – Partially ordered vector space, ordered as a latticePages displaying short descriptions of redirect targets
References
[edit ]Bibliography
[edit ]- Narici, Lawrence; Beckenstein, Edward (2011). Topological Vector Spaces. Pure and applied mathematics (Second ed.). Boca Raton, FL: CRC Press. ISBN 978-1584888666. OCLC 144216834.
- Schaefer, Helmut H.; Wolff, Manfred P. (1999). Topological Vector Spaces. GTM. Vol. 8 (Second ed.). New York, NY: Springer New York Imprint Springer. ISBN 978-1-4612-7155-0. OCLC 840278135.