We prove that the class of Banach function lattices in which all relatively weakly compact sets are equi-integrable (i.e. spaces satisfying Dunford–Pettis criterion) coincides with 1-disjointly homogeneous lattices. New examples such provided. Furthermore, it is shown criterion equivalent to de la Valleé Poussin rearrangement invariant on interval. Finally, results applied characterize pointwis...

‎In this paper‎, ‎we characterize the class of orthogonality preserving operators on an infinite-dimensional Hilbert space $H$ as scalar multiples of unitary operators between $H$ and some closed subspaces of $H$‎. ‎We show that any circle (centered at the origin) is the spectrum of an orthogonality preserving operator‎. ‎Also‎, ‎we prove that every compact normal operator is a strongly orthogo...

Assuming Jensen's diamond principle (⋄) we construct for every natural number n>0 a compact Hausdorff space K such that whenever the Banach spaces C(K) and C(L) are isomorphic some L, then covering dimension of L is equal to n. The constructed separable connected, has few operators i.e. bounded linear operator T:C(K)→C(K) form T(f)=fg+S(f), where g∈C(K) S weakly compact.