Rewrite Bellman-Ford and min-cost flow, especially to stop the latter from crashing.
[match/match.git] / program / ProposalMatcher.hs
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967c39ef 1module ProposalMatcher where
5a07db44 2import NaiveMinCostFlow
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3import Data.Array.IArray
4import Data.Graph.Inductive.Graph
5import Data.Graph.Inductive.Tree
6import Data.List
7
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8import Instance
9import ProposalMatcherConfig
d7d9561e 10
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11prefBoringness p = if prefIsVeryBoring p then 2
12 else if prefIsBoring p then 1 else 0
13prefExpertness p = if prefIsExpert p then 2
14 else if prefIsKnowledgeable p then 1 else 0
15
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16data REdge = REdge {
17 reIdx :: Int,
18 reCap :: Int,
19 reCost :: Wt
20}
21
22instance Show REdge where
23 show (REdge idx cap cost) = "#" ++ (show idx) ++ ": "
24 ++ (show cap) ++ " @ " ++ (show cost)
25
26data ReductionResult = ReductionResult {
27 rrGraph :: Gr () REdge,
28 rrSource :: Node,
29 rrSink :: Node,
30 rrEIdxBounds :: (Int, Int),
31 rrEDIdx :: (Int, Int) -> Int
32}
33
34-- Hack: show as much of the reduction result as we easily can
35data RR1 = RR1 (Gr () REdge) Node Node (Int, Int) deriving Show
36instance Show ReductionResult where
37 show (ReductionResult g so si eib _) = show (RR1 g so si eib)
38
39indexEdges :: Int -> [(Int, Int, REdge)] -> (Int, [(Int, Int, REdge)])
40indexEdges i [] = (i, [])
41indexEdges i ((v1, v2, re):es) =
42 let (imax, ies) = indexEdges (i+1) es in
43 (imax, (v1, v2, re{ reIdx = i }) : ies)
44
45doReduction :: Instance -> ReductionResult
967c39ef 46doReduction (Instance numRvrs numProps rloadA prefA) =
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47 let
48 source = 0
49 sink = 1
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50 rvrNode i boringness = 2 + 3*i + boringness
51 propNode j expertness = 2 + 3*numRvrs + 3*j + expertness
52 numNodes = 2 + 3*numRvrs + 3*numProps
5a07db44 53 edIdx (i, j) = i*numProps + j
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54 in
55 let
2e7d5426 56 totalReviews = reviewsEachProposal * numProps
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57 totalRelativeLoad = foldl (+) 0 (map (rloadA !) [0 .. numRvrs - 1])
58 targetLoad i = ceiling (numAsWt totalReviews * (rloadA ! i) / totalRelativeLoad)
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59 -- A...H refer to idea book p.429
60 edgesABC = do
d7d9561e 61 i <- [0 .. numRvrs - 1]
2e7d5426 62 let tl = targetLoad i
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63 let freeEdgeA = (source, rvrNode i 0, REdge undefined tl 0)
64 let nonfreeEdgesA = do
65 l <- [tl .. tl + loadTolerance - 1]
66 let costA = marginalLoadCost ((numAsWt (l - tl) + 1/2) / numAsWt loadTolerance)
67 [(source, rvrNode i 0, REdge undefined 1 costA)]
68 let edgesBC = do
69 l <- [0 .. tl + loadTolerance - 1]
70 let costB = marginalBoringCost ((numAsWt l + 1/2) / numAsWt tl)
71 let edgeB = (rvrNode i 0, rvrNode i 1, REdge undefined 1 costB)
72 let costC = marginalVeryBoringCost ((numAsWt l + 1/2) / numAsWt tl)
73 let edgeC = (rvrNode i 1, rvrNode i 2, REdge undefined 1 costC)
74 [edgeB, edgeC]
75 [freeEdgeA] ++ nonfreeEdgesA ++ edgesBC
2e7d5426 76 edgesD = do
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77 i <- [0 .. numRvrs - 1]
78 j <- [0 .. numProps - 1]
967c39ef 79 let pref = prefA ! (i, j)
d7d9561e 80 if prefIsConflict pref
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81 then []
82 else [(rvrNode i (prefBoringness pref),
83 propNode j (prefExpertness pref),
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84 REdge (edIdx (i, j)) 1 (assignmentCost pref))]
85 edgesEFGH = do
d7d9561e 86 j <- [0 .. numProps - 1]
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87 let edgeE = (propNode j 2, propNode j 0, REdge undefined 1 (-expertBonus))
88 let edgeF = (propNode j 2, propNode j 1, REdge undefined reviewsEachProposal 0)
89 let edgeGFirst = (propNode j 1, propNode j 0, REdge undefined 1 (-knowledgeableBonus))
90 let edgeGRest = (propNode j 1, propNode j 0, REdge undefined (reviewsEachProposal-1) 0)
91 let edgeH = (propNode j 0, sink, REdge undefined reviewsEachProposal 0)
92 [edgeE, edgeF, edgeGFirst, edgeGRest, edgeH]
2e7d5426 93 theNodes = [(x, ()) | x <- [0 .. numNodes - 1]]
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94 -- Index the non-D edges
95 unindexedEdges = edgesABC ++ edgesEFGH
96 (imax, reindexedEdges) = indexEdges (numRvrs*numProps) unindexedEdges
97 theEdges = edgesD ++ reindexedEdges
d7d9561e 98 in
5a07db44 99 ReductionResult (mkGraph theNodes theEdges) source sink (0, imax-1) edIdx
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100
101todo = undefined
102-- Returns a list of reviews as ordered pairs (reviewer#, proposal#).
2e7d5426 103doMatching :: Instance -> [(Int, Int)]
967c39ef 104doMatching inst@(Instance numRvrs numProps _ _) =
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105 -- Copied from doReduction. There should be a better way to get these here.
106 let
107 source = 0
108 sink = 1
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109 rvrNode i boringness = 2 + 3*i + boringness
110 propNode j expertness = 2 + 3*numRvrs + 3*j + expertness
111 firstPropNode = propNode 0 0
112 idPropNode n = (n - (2 + 3*numRvrs)) `div` 3
113 numNodes = 2 + 3*numRvrs + 3*numProps
d7d9561e 114 in
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115 let ReductionResult graph source sink idxBounds edIdx = doReduction inst in
116 let flowArray = minCostFlow idxBounds reIdx reCap reCost graph (source, sink) in
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117 let pairs = do
118 i <- [0 .. numRvrs - 1]
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119 j <- [0 .. numProps - 1]
120 if flowArray ! edIdx (i, j) == 1
121 then [(i, j)]
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122 else []
123 in
d7d9561e 124 sort pairs -- for prettiness