mathlib3

416edeed - feat(analysis/normed_space/is_R_or_C): add three lemmas on bounds of linear maps over is_R_or_C. (#9827)

feat(analysis/normed_space/is_R_or_C): add three lemmas on bounds of linear maps over is_R_or_C. (#9827) Adding lemmas `linear_map.bound_of_sphere_bound`, `linear_map.bound_of_ball_bound`, `continuous_linear_map.op_norm_bound_of_ball_bound` as a preparation of a PR on Banach-Alaoglu theorem.