Errata for Warehouse & Distribution Science

Each new version fixes all known errors.

Version 0.96

Chapter 7, p. 85: All terms with z_j should be deleted from constraints 7.5 and 7.6 and from the objective function. (Thanks to Yossi Bukchin!)
Chapter 2, typo in the first term of Expression 2.1: It should read 1/k rather than 1/2. (Thank you, Christine Nguyen.)

Chapter 2, pages 16 and 17: Theorem 2.1 and the several paragraphs preceding are wrong because, contrary to my lazy assertion, average utilization is not equal to average inventory divided by average space used. Thanks to Luis Felipe Cardona Olarte of the Universidad ICESI in Cali, Colombia, for pointing this out.
Page 118, Section 8.5.6: The second inequality should be reversed. (Thanks to Wang Zhi for pointing this out.)
Question 9.3 fails to mention that the shelf is of depth 9. Also, the solution is incorrect in the teacher's edition.

Chapter 7: The definition of u_i is ambiguous. It should represent maximum number of pallet locations required by sku i. To get this number, first estimate the maximum number of pallets of sku i, then divide by the number of pallets of sku i per pallet location, and round up. (Thanks to Li Tianjao for catching this.)
Question 7.13 is incomplete and unanswerable as written. (Thanks to Gancheng Wang for catching this.)
Chapter 8: The caption to Table 8.1 (p. 132) contains some gibberish: Delete “Picks are given in person-minutes and”.

page 76: The objective function at the bottom of the page has an error in sign of one of the terms. The objective function expresses the total cost of the forward pick area and so the cost of restocking should be added, not subtracted. (Thanks to Alexandre Blanquet for pointing this out.)
page 137, Figure 9.6: The figure is not wrong but here is a better one, showing the frequency w ith which the 100 most popular pairs of skus appeared in the same customer order. Of these, one pair (#27) almost always constituted a complete customer order. That is, if a customer ordered one of the pair, he almost always ordered the other and nothing else.
Page 300 of the teacher's edition: The column listing number of pallets to allocate should read 3, 2, 8, 2, 37, 1 instead of 2, 2, 4, 1, 18, 1. The remainder of the computations are correct. (Thanks to O. Ozturkoglu, Auburn University, for catching this.)
Page 304 of the teacher's edition: The solution of Question 7.6B is incorrect: Some of the numbers were copied incorrectly. (Thanks to E. Peregrina, Universidad Latina de Panama, for noting this.)

page 61, line 6: The expression for pallet position-years per lane is incomplete. The denominator should be 2D_i rather than 2. (Thanks to Z. He, UMass-Amherst, for pointing this out.)

page 49, Figure 6.2: The blue path is the shorter and the blue location is therefore the more convenient. (Thanks to N. Aguilera, Universidad ICESI, for catching this.)

page 161: There are some typos in intermediate steps of the proof of convergence of a 2-worker bucket brigade.
pages 60, 61: Theorem 6.1 is correct but the derivation is garbled. Only the floor positions should be counted as waste, not the above-ground positions. (Thanks to Bryan Norman, University of Pittsburgh for pointing this out.)

page 180, end of the second paragraph, “Therefore the total travel cannot exceed optimal by more than one revolution.”: This should be 1.5 revolutions (one-half a revolution to match the endpoints of the shortest spanning intervals of the orders, and up to a full revolution to construct the shortest tree spanning the resulting components.