<s>
Ket	B-Application
is	O
an	O
open	O
source	O
algebra	B-Application
editor	I-Application
.	O
</s>
<s>
It	O
is	O
distinct	O
from	O
other	O
editors	O
which	O
focus	O
on	O
automated	O
computation	O
such	O
as	O
integration	O
or	O
equation	O
solving	O
(	O
Mathematica	B-Language
,	O
Maple	B-Language
etc	O
.	O
)	O
</s>
<s>
LaTeX	B-Application
)	O
.	O
</s>
<s>
The	O
focus	O
of	O
Ket	B-Application
is	O
to	O
enable	O
the	O
user	O
to	O
perform	O
algebra	O
quickly	O
and	O
efficiently	O
.	O
</s>
<s>
Ket	B-Application
breaks	O
equation	O
editing	O
into	O
a	O
series	O
of	O
small	O
edits	O
performed	O
by	O
keyboard	O
or	O
mouse	O
gestures	O
.	O
</s>
<s>
Ket	B-Application
maintains	O
three	O
distinct	O
representations	O
of	O
an	O
equation	O
.	O
</s>
<s>
Internally	O
it	O
is	O
most	O
efficient	O
to	O
represent	O
the	O
equation	O
as	O
a	O
Tree	B-Data_Structure
structure	I-Data_Structure
which	O
standardizes	O
direction	O
commands	O
.	O
</s>
<s>
But	O
when	O
writing	O
equation	O
fragments	O
or	O
saving	O
them	O
to	O
file	O
,	O
a	O
custom	O
markdown	O
language	O
is	O
used	O
which	O
merges	O
markdown	O
,	O
LaTeX	B-Application
and	O
plain	O
text	O
mathematical	O
notations	O
as	O
applicable	O
.	O
</s>
<s>
Analogous	O
to	O
a	O
filesystem	O
hierarchy	O
of	O
files	O
and	O
folders	O
within	O
folders	O
,	O
each	O
equation	O
is	O
represented	O
as	O
a	O
Tree	B-Data_Structure
structure	I-Data_Structure
.	O
</s>
<s>
Each	O
equation	O
in	O
Ket	B-Application
is	O
a	O
tree	O
of	O
operations	O
and	O
functions	O
(	O
tree	O
branches	O
)	O
and	O
variables	O
and	O
values	O
(	O
tree	O
leaves	O
)	O
.	O
</s>
<s>
These	O
include	O
reorganizing	O
the	O
tree	B-Data_Structure
structure	I-Data_Structure
and	O
performing	O
simple	O
algebraic	O
operations	O
.	O
</s>
<s>
Ket	B-Application
is	O
a	O
modal	O
editor	O
which	O
means	O
that	O
it	O
changes	O
how	O
it	O
displays	O
information	O
and	O
how	O
the	O
user	O
interacts	O
with	O
it	O
depending	O
on	O
the	O
mode	O
it	O
's	O
in	O
.	O
</s>
