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Inductive and projective limits of normed spaces

Published online by Cambridge University Press:  18 May 2009

John S. Pym
Affiliation:
The UniversitySheffield
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Let {Ui, Uij} be an inductive system of normed linear spaces Ui and continuous linear maps uij; UjUi. (We write ji if uij: UjUi.) An inductive limit of the system with respect to a class of spaces A in and maps f in is a space Uu in Uu and a system uiUu of maps in such that (i) whenever ji, and that (ii) if A is any space in and fi: UiA is any system of maps in for which then there is a unique map f: UuA in such that fi = fo ui for each i. If is the class of all vector spaces and is the class of linear maps, we obtain the algebraic inductive limit, which we denote simply by U. The usual choice is to take to be the class of locally convex spaces and the class of continuous linear maps; the inductive limit UL then always exists [1, § 16 C]. If is again the continuous linear mappings but contains only normed spaces, the corresponding inductive limit UN may not always exist. However, if in addition we require that contains just contractions (norm-decreasing linear mappings), then an inductive limit Uc will exist if every uij is a contraction [2]. We shall give a condition under which these limits coincide (as far as possible), and consider the corresponding condition for projective limits.

Type
Research Article
Copyright
Copyright © Glasgow Mathematical Journal Trust 1968

References

REFERENCES

1.Kelley, J. L. and Namioka, I., Linear Topological Spaces, (Princeton, 1963).Google Scholar
2.Semadini, Z. and Zidenberg, H., Inductive and inverse limits in the category of Banach spaces, Bull. Acad. Polon. Sci. Sér. Sci. Math. Astr. Phys. 13 (1965), 579583.Google Scholar