Polar Functions of Multiparameter Bifractional Brownian Sheets

Let B-H,B-K = {B-H,B-K(t), t is an element of R-+(N)} be an (N, d)-bifractional Brownian sheet with Hurst indices H = (H-1, . . . , H-N) is an element of (0, 1)(N) and K = (K-1, . . . , K-N) is an element of (0, 1](N). The characteristics of the polar functions for B-H,B-K are investigated. The relationship between the class of continuous functions satisfying the Lipschitz condition and the class of polar-functions of B-H,B-K is presented. The Hausdorff dimension of the fixed points and an inequality concerning the Kolmogorov's entropy index for B-H,B-K are obtained. A question proposed by LeGall about the existence of no-polar, continuous functions statisfying the Holder condition is also solved.