From 5a184b4397c0a30e873d3b59f36a7b28d49dca3a Mon Sep 17 00:00:00 2001
From: Ir1d <sirius.caffrey@gmail.com>
Date: Tue, 22 Jan 2019 22:33:16 +0800
Subject: [PATCH] =?utf8?q?feat:=20add=20Hall=20=E5=AE=9A=E7=90=86?=
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---
 docs/graph/bi-graph.md | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/docs/graph/bi-graph.md b/docs/graph/bi-graph.md
index c463044f..c218765f 100644
--- a/docs/graph/bi-graph.md
+++ b/docs/graph/bi-graph.md
@@ -31,6 +31,10 @@
 
 ### 二分图匹配
 
+#### 霍尔定理
+
+设二部图 $G=<V_1, V_2, E>, |V_1| \leq |V_2|$，则 $G$ 中存在 $V_1$ 到 $V_2$ 的完备匹配当且仅当对于任意的 $S \subset V_1$，均有 $|S|\leq|N(S)|$，其中 $N(S)=\Cup_{v_i \in S}{N(V_i)}$，是 $S$ 的邻域。
+
 #### 最大匹配
 
 #### 最大权匹配
-- 
2.11.0