<s>
Fitch	B-Application
notation	I-Application
,	O
also	O
known	O
as	O
Fitch	O
diagrams	O
(	O
named	O
after	O
Frederic	O
Fitch	O
)	O
,	O
is	O
a	O
notational	O
system	O
for	O
constructing	O
formal	O
proofs	O
used	O
in	O
sentential	O
logics	O
and	O
predicate	O
logics	O
.	O
</s>
<s>
A	O
unique	O
feature	O
of	O
Fitch	B-Application
notation	I-Application
is	O
that	O
the	O
degree	O
of	O
indentation	O
of	O
each	O
row	O
conveys	O
which	O
assumptions	O
are	O
active	O
for	O
that	O
step	O
.	O
</s>
<s>
The	O
following	O
example	O
displays	O
the	O
main	O
features	O
of	O
Fitch	B-Application
notation	I-Application
:	O
</s>
