Bounded Mean Oscillation - Definition

Definition

Definition 1. The mean oscillation of a locally integrable function u (i.e. a function belonging to ) over a hypercube Q in ℝn is defined as the following integral:

where

  • |Q| is the volume of Q, i.e. its Lebesgue measure
  • uQ is the average value of u on the cube Q, i.e.
.

Definition 2. A BMO function is any function u belonging to whose mean oscillation has a finite supremum over the set of all cubes Q contained in ℝn.

Note. The use of cubes Q in ℝn as the integration domains on which the mean oscillation is calculated, is not mandatory: Wiegerinck (2001) uses balls instead and, as remarked by Stein (1993, p. 140), in doing so a perfectly equivalent of definition of functions of bounded mean oscillation arises.

Read more about this topic:  Bounded Mean Oscillation

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