tag:blogger.com,1999:blog-593563533834706486.post1961414235215608196..comments2015-02-10T07:23:43.000-05:00Comments on Yet Another Math Programming Consultant: A conference scheduling problemErwin Kalvelagenhttps://plus.google.com/100547539949080099832noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-593563533834706486.post-55424841495966109562009-12-19T21:02:26.319-05:002009-12-19T21:02:26.319-05:00Talk to your teacher or supervisor. He/she is gett...Talk to your teacher or supervisor. He/she is getting paid to help you.Erwin Khttps://www.blogger.com/profile/09496091402502236997noreply@blogger.comtag:blogger.com,1999:blog-593563533834706486.post-6108926303278289082009-12-19T20:58:18.625-05:002009-12-19T20:58:18.625-05:00Hey, I have a VRP Problem and i dont know hoe to s...Hey, I have a VRP Problem and i dont know hoe to solve.<br /><br />Need to develop a MILP model that returns the minimum total travel time.<br /><br />is a chain of supermarkets that are serviced daily by a single distribution center. A fleet<br />of 4 trucks with 20000 pounds of capacity is used to make these deliveries. The daily demand and<br />travel times between distribution center and other store points are as follows. Note that the travel<br />times’ matrix is symmetric. A dash in the table indicates that the connection is not possible.<br /><br />Daily demand (pounds)<br />Store 1 2 3 4 5 6 7 8 9<br />DC 6000 3000 4000 7000 5000 2000 3000 8000 10000<br /><br /><br />Travel times (minutes)<br />Store 1 2 3 4 5 6 7 8 9<br /><br />DC 0 10 20 - 5 20 25 25 30 5<br />1 0 5 10 5 10 15 15 20 10<br />2 0 20 15 - 10 10 15 15<br />3 0 5 20 25 - 30 10<br />4 0 15 25 25 25 5<br />5 0 10 - 15 15<br />6 0 5 - 20<br />7 0 5 20<br />8 0 25<br />9 0<br /><br />Can you helpAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-593563533834706486.post-33140718900181965132009-12-12T12:16:14.547-05:002009-12-12T12:16:14.547-05:00Yes there are standard formulations for this. Basi...Yes there are standard formulations for this. Basically, count the number of times the binary variable switches from 0 to 1. This number should be <= 1.Erwin Khttps://www.blogger.com/profile/09496091402502236997noreply@blogger.comtag:blogger.com,1999:blog-593563533834706486.post-87449021685263092372009-12-12T08:41:34.400-05:002009-12-12T08:41:34.400-05:00`` It is often the simplest to start with a single...`` It is often the simplest to start with a single large multidimensional “cube” (our variable x(t,p,s)), and then derive auxiliary variables from that cube (our variables xts, xtp). ``<br /><br />Interesting and clear explanation - thanks!<br /><br />I have a question concerning this formulation, how would you model that the timeslots have to be conseconsecutive? E.g. a person visits four talks in his/her five available slots (one talk each slot), then timeslots {1,2,3,4} and {2,3,4,5} are valid, but {1,2,4,5} is not. Is there a straightforward method to formulate this using binary variables?Anonymousnoreply@blogger.com