We explore extreme contractions on finite-dimensional polygonal Banach spaces, from the point of view of attainment of norm of a linear operator. We prove that if XX is an nn-dimensional polygonal Banach space and YY is any normed linear space and TL(X,Y)T \in L(X,Y) is an extreme contraction, then TT attains norm at nn linearly independent extreme points of BXB_{X}. Moreover, if TT attains norm at nn linearly independent extreme points x1,x2,,xnx_1, x_2, \ldots, x_n of BXB_X and does not attain norm at any other extreme point of BXB_X, then each TxiTx_i is an extreme point of BY.B_Y. We completely characterize extreme contractions between a finite-dimensional polygonal Banach space and a strictly convex normed linear space. We introduce L-P property for a pair of Banach spaces and show that it has natural connections with our present study. We also prove that for any strictly convex Banach space XX and any finite-dimensional polygonal Banach space YY, the pair (X,Y)(X,Y) does not have L-P property. Finally, we obtain a characterization of Hilbert spaces among strictly convex Banach spaces in terms of L-P property.

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Debmalya Sain

Dept. of Mathematics, Indian Institute of Science, Bengaluru 560012, Karnataka, India

saindebmalya@gmail.com

Kallol Paul

Dept. of Mathematics, Jadavpur University, Kolkata 700032, West Bengal, India

kalloldada@gmail.com

D. Sain, A. Ray, K. Paul. “Extreme Contractions on Finite-Dimensional Polygonal Banach Spaces.” Journal of Convex Analysis 26 (2019), No. 3, 877–885.