Abstract: | If Au = - div(a(x, Du)) is a monotone operator defined on the Sobolev space W1,P(Rn, 1 < p < + , with a(x,0) = 0 for a.e. x Rn, the capacity C_A(E,F) relative to A can be defined for every pair (E,F) of bounded sets in Rn with E F. The main properties of the set function CA(E,F) are investigated. In particular it is proved that CA(E,F) is increasing and countably subadditive with respect to E, decreasing with respect to F, and continuous, in a suitable sense, with respect to E and F. |