TY - JOUR AU - Mustăţa, Costică PY - 2003/08/01 Y2 - 2024/03/28 TI - On the uniqueness of extension and unique best approximation in the dual of an asymmetric normed linear space JF - Rev. Anal. Numér. Théor. Approx. JA - Rev. Anal. Numér. Théor. Approx. VL - 32 IS - 2 SE - Articles DO - 10.33993/jnaat322-747 UR - https://ictp.acad.ro/jnaat/journal/article/view/2003-vol32-no2-art7 SP - 187-192 AB - <pre>A well known result of R. R. Phelps (1960) asserts that in order</pre><pre> that every linear continuous functional, defined on a subspace \(<span>Y\)</span></pre><pre> of a real normed space \(<span>X\)</span>, have a unique norm preserving</pre><pre> extension it is necessary and sufficient that its annihilator</pre><pre><span> \(Y^\bot\)</span> be a Chebyshevian subspace of \(<span>X^\ast\)</span>. The aim of this</pre><pre> note is to show that this result holds also in the case of spaces</pre><pre> with asymmetric norm.</pre> ER -