StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
426234
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
4
CommunityOwnedDate
CreationDate
2009-01-08T22:15:12.677
FavoriteCount
0
LastActivityDate
2009-01-08T22:46:31.680
LastEditDate
2009-01-08T22:46:31.680
LastEditorUserId
34502
OwnerUserId
34502
ParentId
426173
PostTypeId
2
Score
2
ViewCount
0
LastEditorDisplayName
David Norman
text
Body
This can be written as a <a href="http://en.wikipedia.org/wiki/Linear_programming" rel="nofollow noreferrer">linear programming</a> problem. For most 'typical' problems, the simplex method is a fast, relatively simple way to solve such problems, or there are open source LP solvers available. For your example: Let 0 <= xi <= 1 <ul> <li>x1 = One if one coupon is spent on item 1, zero otherwise </li> <li>x2 = One if two coupons are spent on item 1, zero otherwise </li> <li>x3 = One if one coupon is spent on item 2, zero otherwise</li> <li>x4 = One if two coupons are spent on item 2, zero otherwise </li> <li>x5 = One if three coupons are spent on item 3, zero otherwise </li> <li>...</li> </ul> Assume that if I spend two coupons on item 1, then both x1 and x2 are one. This implies the constraint <ul> <li>x1 >= x2</li> </ul> With similar constraints for the other items, e.g., <ul> <li>x3 >= x4</li> <li>x4 >= x5</li> </ul> The amount saved is <ul> <li>Saved = 10 x1 + 5 x2 + 0 x3 + 5 x4 + 10 x5 + ...</li> </ul> If you want to find the most money saved with a fixed number of coupons, then you want to minimize Saved subject to the constraints above and the additional constraint: <ul> <li>coupon count = x1 + x2 + x3 + ...</li> </ul> This works for any matrix and number of items. Changing notation (and feeling sad that I can't do subscripts), let 0 <= y_ij <= 1 be one if j coupons are spent on item number i. The we have the constraints <ul> <li>y_i(j-1) >= y_ij</li> </ul> If the amount saved from spending j coupons on item i is M_ij, where we define M_i0 = 0, then maximize <ul> <li>Saved = Sum_ij (M_ij - M_i(j-1)) y_ij</li> </ul> subject to the above constraints and <ul> <li>coupon count = Sum_ij y_ij</li> </ul> (The italics formatting doesn't seem to be working here)
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POWhat is the algorithm to determine the best way to distribute these coupons?
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USDavid Norman
UserOwnerUserId
1. USDavid Norman
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.