1. Martingale type, the Gamlen-Gaudet construction and a greedy algorithm.
- Author
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Kazaniecki, Krystian and Müller, Paul F.X.
- Subjects
- *
MARTINGALES (Mathematics) , *BANACH spaces , *COMMERCIAL space ventures , *HARDY spaces , *GREEDY algorithms - Abstract
In the present paper we identify those filtered probability spaces (Ω , F , (F n) , P) that determine already the martingale type of a Banach space X. We isolate intrinsic conditions on the filtration (F n) of purely atomic σ -algebras which determine that the upper ℓ p estimates ‖ f ‖ L p (Ω , X) p ⩽ C p (‖ E (f | F 0) ‖ L p (Ω , X) p + ∑ n = 1 ∞ ‖ E (f | F n) − E (f | F n − 1) ‖ L p (Ω , X) p) , f ∈ L p (Ω , X) imply that the Banach space X is of martingale type p. Our paper complements G. Pisier's investigation [12] and continues the work by S. Geiss and second named author in [3]. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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