Minimal projections onto subspaces with codimension 2. (English) Zbl 1385.46005
Summary: In this article, the relationship between absolute projection constants with dimension \(n\) and with codimension \(n\) is given. In particular, bounds from below are found for absolute projection constants with codimension 2. Also, exact formulas for minimal projections in this case are given. It is shown that these minimal projections are not unique.
MSC:
| 46B03 | Isomorphic theory (including renorming) of Banach spaces |
| 41A65 | Abstract approximation theory (approximation in normed linear spaces and other abstract spaces) |
| 46B28 | Spaces of operators; tensor products; approximation properties |
| 41A35 | Approximation by operators (in particular, by integral operators) |
