voula@utcsri.UUCP (Voula Vanneli) (03/19/85)
UNIVERSITY OF TORONTO DEPARTMENT OF COMPUTER SCIENCE (_G_B = _G_a_l_b_r_a_i_t_h _B_u_i_l_d_i_n_g, _3_5 _S_t. _G_e_o_r_g_e) Professor George Steiner School of Business, McMaster University "Searching and Scheduling in Ordered Sets" Abstract We discuss the problem of retrieving data from ordered data structures and its relationship to many well-known pre- cedence constrained scheduling problems. The complexity of all these problems depends on how efficiently we can enumerate the ideals of the underlying ordered structure. As a special case of this generally difficult problem, we present a labelling scheme which counts the ideals of a two-dimensional partial order in polynomial time. Based on this scheme, we show how the central element of a two- dimensional partial order can be located in polynomial time.