From 636f7c4795394fd7be4f04d079fce0355e5d190c Mon Sep 17 00:00:00 2001
From: Antti H S Laaksonen <ahslaaks@cs.helsinki.fi>
Date: Mon, 17 Apr 2017 20:22:56 +0300
Subject: [PATCH] More about segment tree origin

---
 chapter09.tex | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/chapter09.tex b/chapter09.tex
index 9121590..63eb4c0 100644
--- a/chapter09.tex
+++ b/chapter09.tex
@@ -744,9 +744,10 @@ takes $O(1)$ time using bit operations.
 
 \index{segment tree}
 
-A \key{segment tree}\footnote{The origin of this structure is unknown.
+A \key{segment tree}\footnote{Quite similar structures were used
+in the late 1970's to solve geometric problems \cite{ben80}.
 The bottom-up-implementation in this chapter corresponds to
-the implementation in \cite{sta06}.} is a data structure
+that in \cite{sta06}.} is a data structure
 that supports two operations:
 processing a range query and
 modifying an element in the array.