English

Small Diameter Properties In Ideals of Banach Spaces

Functional Analysis 2021-09-13 v1

Abstract

A Banach space has the ball huskable property (BHPBHP) if the closed unit ball has weakly open sets of arbitrarily small diameter. We can analogously define ww^*-BHPBHP in the dual space. In this short note, we study these properties in the context of ideals in Banach spaces. The notion of an ideal, was introduced by Godefroy, Kalton and Saphar. We show that if a Banach space XX has BHP,BHP, then any MM-ideal of XX also has BHP.BHP. We further show that if YY is an MM-ideal of X,X, then YY^* has ww^*-BHPBHP implies XX^* has ww^{*}-BHP.BHP. We use this result to prove that for a compact Hausdorff space KK which has an isolated point, XX has BHPBHP whenever C(K,X)C(K,X) has BHPBHP and XX^* has ww^{*}-BHPBHP implies C(K,X)C(K,X)^* has ww^{*}-BHP.BHP. We also prove that ww^*-BHPBHP can be lifted from YY^* to XX^* provided YY is a strict ideal of XX. Lastly, we show that if YY is an almost isometric ideal of X,X, then BHPBHP can be lifted from YY to X.X. We obtain similar results for ball dentable property (BDPBDP) and ball small combination of slices Property (BSCSPBSCSP) as well.

Keywords

Cite

@article{arxiv.2109.04963,
  title  = {Small Diameter Properties In Ideals of Banach Spaces},
  author = {Sudeshna Basu and Susmita Seal},
  journal= {arXiv preprint arXiv:2109.04963},
  year   = {2021}
}

Comments

arXiv admin note: text overlap with arXiv:2011.14591