fair: Fix bug in increase algo to match decrease algo

timgott · Jun 30, 2024 · 0be117d · 0be117d
1 parent 6bd1447
commit 0be117d
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Showing 2 changed files with 8 additions and 9 deletions.
diff --git a/socialchoice/src/algo.ts b/socialchoice/src/algo.ts
@@ -201,19 +201,18 @@ export function findSwappableTowards(
   let connectedAgents = new Set<Agent>();
   let connectedItems = new Set<Item>();
   let predecessor = new Map<Agent, [Item, Agent]>();
-  bfsSimple(root, (agent: Agent) => {
+  bfsFold(root, () => null, (agent: Agent, parent: [Item, Agent] | null) => {
     connectedAgents.add(agent);
-
+    if (parent) {
+      predecessor.set(agent, parent);
+    }
     // find alternating continuation (mbb, then allocation)
     const mbb = mbbSets.get(agent)!;
-    const children: Agent[] = [];
+    const children: [Agent, [Item, Agent]][] = [];
     for (const item of mbb) {
       connectedItems.add(item);
       const owner = getOwner(item);
-      if (!connectedAgents.has(owner)) {
-        children.push(owner);
-        predecessor.set(owner, [item, agent]);
-      }
+      children.push([owner, [item, agent]]);
     }
 
     return children;

diff --git a/socialchoice/src/main.allocation.ts b/socialchoice/src/main.allocation.ts
@@ -19,7 +19,7 @@ import {
   computeMBBSet,
   findBudgetViolatorsUpTo1,
   findLeastSpenders,
-  findSwappableComponent,
+  findSwappableTowards,
   improveAllocationStep,
 } from "./algo";
 import {
@@ -253,7 +253,7 @@ class AllocationGraph {
     let mbbSets = mapFromFunction<Agent,Set<Item>>(
       model.agents, a => computeMBBSet(a, model.market.prices)
     );
-    let swapComponent = findSwappableComponent(leastSpenders, model.market, mbbSets);
+    let swapComponent = findSwappableTowards(leastSpenders, model.market, mbbSets);
     for (let [agent, agentNode] of this.agentMap) {
       // connect MBB set
       let mbbSet = ensured(mbbSets.get(agent));