Abstract
The intersection of an arbitrary strict sun M in C(Q) with a closed span Π ⊂ C(Q) (in particular, with a closed ball) is shown to be a strict protosun, provided that the natural condition M ∩ int Π ≠ Ø is satisfied. This property is shown to characterize closed spans in C(Q).
Similar content being viewed by others
References
L. P. Vlasov, “Approximative Properties of Sets in Normed Linear Spaces,” Uspekhi Matem. Nauk 28(6), 3 (1973) [Russ. Math. Surv. 28 (6), 1 (1973)].
B. Brosowski and R. Wegmann, “Charakterisierung bester Approximationen in normierten Vektorraumen,” J. Ap-prox. Theory, 3(4), 369 (1970).
W. Yang, Ch. Li, and G. A. Watson, “Characterization and Uniqueness of Nonlinear Uniform Approximation,” Proc. Edinburgh Math. Soc. 40, 473 (1997).
V. A. Koshcheev, “Connectedness and Solar Properties of Sets in Normed Linear Spaces,” Matem. Zametki 19(2), 267 (1976) [Math. Notes 19 (2), 158 (1976)].
A. P. Alimov, “Connectedness of Suns in the Space c 0,” Izvestiya Rus. Akad. Nauk, Ser. Matem. 69(4), 3 (2005) [Izvestiya: Math. 69 (4), 651 (2005)].
A. P. Alimov, “Preservation of Approximative Properties of Subsets of Chebyshev Sets and Suns in ℓ∞(n),” Izvestiya Rus. Akad. Nauk, Ser. Matem. 70(5), 3 (2006) [Izvestiya: Math. 70 (5), 857 (2006)].
A. P. Alimov, “Monotone Path-Connectedness of Chebyshev Sets in the Space C(Q),” Matem. Sborn. 197(9), 3 (2006) [Sbornik: Math. 197 (9), 1259 (2006)].
A. P. Alimov, “Preservation of Approximative Properties of Subsets of Chebyshev Sets in a Plane,” Vestnik Mosk. Univ., Matem. Mekhan., No. 4, 46 (2008) [Moscow Univ. Math. Bulletin 63 (5), 198 (2008)].
A. A. Vasil’eva, “Closed Spans in Vector-Valued Function Spaces and their Approximative Properties,” Izvestiya Rus. Akad. Nauk, Ser. Matem. 68(4), 75 (2004) [Izvestiya: Math. 68 (4), 709 (2004)].
A. P. Alimov, “Geometrical Characterization of Strict Suns in ℓ∞(n),” Matem. Zametki 70(1), 3 (2001) [Math. Notes 70 (1), 3 (2001)].
A. R. Alimov, “Characterizations of Chebyshev sets in c 0,” J. Approx. Theory 129, 217 (2004).
A. R. Alimov and V. Yu. Protasov, “Separability of Convex Sets by Extreme Hyperplanes,” Fundam. Prikl. Matem. 17(4), 3 (2012).
Author information
Authors and Affiliations
Additional information
Original Russian Text © A.P. Alimov, 2012, published in Vestnik Moskovskogo Universiteta, Matematika. Mekhanika, 2012, Vol. 67, No. 6, pp. 16–19.
About this article
Cite this article
Alimov, A.P. Bounded strict solar property of strict suns in the space C(Q) . Moscow Univ. Math. Bull. 68, 14–17 (2013). https://doi.org/10.3103/S0027132213010038
Received:
Published:
Issue Date:
DOI: https://doi.org/10.3103/S0027132213010038