Combinatorial Optimization comprises research-level linear and combinatorial problems together with algorithms and solution-procedures to solve them. The growing need of the industry and the increase in complexity of conglomerates and multinationals entail focus on two very significant classes of problems; namely Transportation and Assignment Problems included in this volume. Far-reaching variants of these problems like the Multi-index and Multi-objective Problems, Bulk Transportation Problems, Flow and Budgetary Constrained Transportation Problems and the Three-Axial Sums Problems are investigated and analysed. Extensions to the Two-Stage and Bi-level Allocation Problems form the salient features of the book. Practical applications of the problems examined are also discussed. This volume opens new avenues for research in the field of allocation problems.