This volume considers various applications of equimeasurable function
rearrangements to the "best constant"-type problems. It presents several
classical theorems along with some very recent results. Coverage
includes a product-space extension of the Rising Sun lemma, a
product-space version of the John-Nirenberg inequality for bounded mean
oscillation functions with sharp exponent, and sharp embedding theorems
for Muckenhoupt, Gurov-Reshetnyak, and Gehring classes.