<s>
A	O
binary	B-Algorithm
expression	I-Algorithm
tree	I-Algorithm
is	O
a	O
specific	O
kind	O
of	O
a	O
binary	O
tree	O
used	O
to	O
represent	O
expressions	O
.	O
</s>
<s>
Two	O
common	O
types	O
of	O
expressions	O
that	O
a	O
binary	B-Algorithm
expression	I-Algorithm
tree	I-Algorithm
can	O
represent	O
are	O
algebraic	O
and	O
boolean	O
.	O
</s>
<s>
Like	O
any	O
binary	O
tree	O
,	O
each	O
node	O
of	O
a	O
binary	B-Algorithm
expression	I-Algorithm
tree	I-Algorithm
has	O
zero	O
,	O
one	O
,	O
or	O
two	O
children	O
.	O
</s>
<s>
This	O
restricted	O
structure	O
simplifies	O
the	O
processing	O
of	O
expression	B-Algorithm
trees	I-Algorithm
.	O
</s>
<s>
Algebraic	O
expression	B-Algorithm
trees	I-Algorithm
represent	O
expressions	O
that	O
contain	O
numbers	O
,	O
variables	O
,	O
and	O
unary	O
and	O
binary	O
operators	O
.	O
</s>
<s>
The	O
operators	O
are	O
contained	O
in	O
the	O
internal	O
nodes	O
of	O
the	O
tree	O
,	O
with	O
the	O
numbers	O
and	O
variables	O
in	O
the	O
leaf	B-Application
nodes	I-Application
.	O
</s>
<s>
The	O
nodes	O
of	O
binary	O
operators	O
have	O
two	O
child	B-Data_Structure
nodes	I-Data_Structure
,	O
and	O
the	O
unary	O
operators	O
have	O
one	O
child	B-Data_Structure
node	I-Data_Structure
.	O
</s>
