A. Manoussakis and A. Pelczar-Barwacz, "Operators in tight by support Banach spaces," J. London Math. Soc., vol. 93, no. 2, pp. 464-480, Apr. 2016. doi: 10.1112/jlms/jdv072
https://doi.org/10.1112/jlms/jdv072
Answering the question of W. T. Gowers, we give an example of a bounded operator on a subspace of Gowers unconditional space, which is not a strictly singular perturbation of a restriction of a diagonal operator. We make some observations on operators in arbitrary tight by support Banach space, showing in particular that in such a space no two isomorphic infinitely dimensional subspaces form a direct sum.