fix typo and join two paragraphs
diff --git a/Doc/ref/ref4.tex b/Doc/ref/ref4.tex
index b993266..dbd6a2f 100644
--- a/Doc/ref/ref4.tex
+++ b/Doc/ref/ref4.tex
@@ -80,8 +80,7 @@
uses of the name within the block are treated as references to the
current block. This can lead to errors when a name is used within a
block before it is bound.
-
-The previous rule is a subtle. Python lacks declarations and allows
+This rule is subtle. Python lacks declarations and allows
name binding operations to occur anywhere within a code block. The
local variables of a code block can be determined by scanning the
entire text of the block for name binding operations.