https://doi.org/10.4169/college.math.j.45.1.054 https://www.jstor.org/stable/10.4169/college.math.j.45.1.054 Summary We present a result of Rosenthal, which shows ...

Let X be a normed linear space, Un an n-dimensional Chebyshev subspace of X. For f ∈ X denote by p(f) ∈ Un its best approximation in Un. The problem of strong unicity consists in estimating how fast ...

Harmonic functions, defined as twice continuously differentiable functions satisfying Laplace’s equation, have long been a subject of intense study in both pure and applied mathematics. Their ...