<s>
In	O
theoretical	O
computer	O
science	O
and	O
formal	O
language	O
theory	O
,	O
a	O
ranked	B-Application
alphabet	I-Application
is	O
a	O
pair	O
of	O
an	O
ordinary	O
alphabet	O
F	O
and	O
a	O
function	O
Arity	O
:	O
F	O
→	O
.	O
</s>
<s>
Higher	O
arities	O
lead	O
to	O
proper	O
trees	B-Application
.	O
</s>
