<s>
Impro-Visor	B-Application
is	O
an	O
educational	O
tool	O
for	O
creating	O
and	O
playing	O
a	O
lead	O
sheet	O
,	O
with	O
a	O
particular	O
orientation	O
toward	O
representing	O
jazz	B-Device
solos	O
.	O
</s>
<s>
The	O
philosophy	O
of	O
Impro-Visor	B-Application
is	O
to	O
provide	O
a	O
tool	O
to	O
help	O
musicians	O
construct	O
jazz	B-Device
solos	O
over	O
chord	O
progressions	O
.	O
</s>
<s>
It	O
includes	O
a	O
database	O
capability	O
for	O
creating	O
,	O
saving	O
,	O
and	O
recalling	O
licks	O
,	O
as	O
well	O
as	O
a	O
lick	O
generation	O
capability	O
based	O
on	O
a	O
user-modifiable	O
grammar	B-General_Concept
.	O
</s>
<s>
More	O
recent	O
versions	O
of	O
Impro-Visor	B-Application
include	O
auto-generated	O
playback	O
accompaniment	O
in	O
various	O
styles	O
,	O
and	O
a	O
style	O
extraction	O
(	O
from	O
MIDI	O
)	O
capability	O
.	O
</s>
<s>
Impro-Visor	B-Application
saves	O
lead	O
sheets	O
in	O
a	O
textual	O
notation	O
,	O
and	O
lead	O
sheets	O
may	O
be	O
created	O
from	O
that	O
notation	O
as	O
well	O
as	O
by	O
point-and-click	O
.	O
</s>
<s>
The	O
notation	O
was	O
designed	O
to	O
be	O
friendly	O
to	O
the	O
jazz	B-Device
musician	O
,	O
by	O
resembling	O
directly	O
what	O
appears	O
on	O
the	O
lead	O
sheet	O
staff	O
.	O
</s>
<s>
Impro-Visor	B-Application
categorizes	O
tones	O
that	O
can	O
be	O
played	O
over	O
any	O
chord	O
into	O
one	O
of	O
four	O
categories	O
.	O
</s>
<s>
The	O
other	O
key	O
ingredient	O
is	O
a	O
context-free	O
grammar	B-General_Concept
having	O
terminal	O
symbols	O
for	O
each	O
of	O
the	O
four	O
categories	O
,	O
along	O
with	O
a	O
few	O
other	O
terminal	O
symbols	O
for	O
convenience	O
.	O
</s>
<s>
The	O
grammar	B-General_Concept
defines	O
ways	O
in	O
which	O
the	O
melody	O
space	O
can	O
be	O
filled	O
probabilistically	O
by	O
tones	O
of	O
various	O
durations	O
.	O
</s>
<s>
By	O
associating	O
a	O
probability	O
with	O
each	O
grammar	B-General_Concept
rule	O
,	O
the	O
distribution	O
of	O
generated	O
melodies	O
can	O
be	O
controlled	O
,	O
for	O
example	O
to	O
create	O
melodies	O
that	O
are	O
simple	O
or	O
complex	O
,	O
relatively	O
consonant	O
or	O
dissonant	O
,	O
etc	O
.	O
</s>
<s>
The	O
user	O
indicates	O
the	O
chord	O
progression	O
,	O
and	O
the	O
grammar	B-General_Concept
drives	O
the	O
melody	O
generation	O
over	O
that	O
progression	O
.	O
</s>
<s>
This	O
particular	O
grammar	B-General_Concept
is	O
constructed	O
so	O
as	O
not	O
to	O
produce	O
any	O
discordant	O
notes	O
(	O
notes	O
in	O
the	O
"	O
other	O
"	O
category	O
above	O
)	O
,	O
thus	O
no	O
red	O
notes	O
appear	O
in	O
the	O
figure	O
.	O
</s>
<s>
Version	O
4	O
added	O
a	O
feature	O
for	O
learning	O
a	O
grammar	B-General_Concept
from	O
a	O
corpus	O
of	O
transcribed	O
solos	O
.	O
</s>
<s>
The	O
learned	O
grammar	B-General_Concept
loosely	O
approximates	O
the	O
playing	O
style	O
of	O
the	O
soloist	O
by	O
creating	O
abstract	O
melodies	O
from	O
the	O
solos	O
,	O
which	O
can	O
be	O
re-instantiated	O
into	O
similar	O
melodies	O
through	O
the	O
grammar	B-General_Concept
.	O
</s>
<s>
Connections	O
between	O
learned	O
abstract	O
melodic	O
fragments	O
are	O
represented	O
as	O
a	O
Markov	O
chain	O
,	O
which	O
is	O
encoded	O
into	O
the	O
stochastic	B-General_Concept
context-free	I-General_Concept
grammar	I-General_Concept
.	O
</s>
<s>
Impro-Visor	B-Application
automatically	O
creates	O
accompaniment	O
,	O
such	O
as	O
piano	O
,	O
bass	O
,	O
and	O
drums	O
,	O
from	O
the	O
chord	O
sequence	O
on	O
a	O
leadsheet	O
(	O
a	O
capability	O
similar	O
to	O
,	O
but	O
currently	O
not	O
as	O
full-featured	O
as	O
that	O
of	O
Band-in-a-Box	B-Application
)	O
.	O
</s>
<s>
Impro-Visor	B-Application
analyzes	O
jazz	B-Device
lead	O
sheets	O
to	O
produce	O
a	O
roadmap	O
of	O
the	O
tune	O
.	O
</s>
