Abstract
In this paper we characterize the integrability and the non-existence of limit cycles of Kolmogorov systems of the form
x
′
=
x
(
B
1
(
x
,
y
)
ln
|
A
3
(
x
,
y
)
A
4
(
x
,
y
)
|
+
B
3
(
x
,
y
)
ln
|
A
1
(
x
,
y
)
A
2
(
x
,
y
)
|
)
,
y
′
=
y
(
B
2
(
x
,
y
)
ln
|
A
5
(
x
,
y
)
A
6
(
x
,
y
)
|
+
B
3
(
x
,
y
)
ln
|
A
1
(
x
,
y
)
A
2
(
x
,
y
)
|
)
\matrix{{x' = x\left( {{B_1}\left( {x,y} \right)\ln \left| {{{{A_3}\left( {x,y} \right)} \over {{A_4}\left( {x,y} \right)}}} \right| + {B_3}\left( {x,y} \right)\ln \left| {{{{A_1}\left( {x,y} \right)} \over {{A_2}\left( {x,y} \right)}}} \right|} \right),} \hfill \cr {y' = y\left( {{B_2}\left( {x,y} \right)\ln \left| {{{{A_5}\left( {x,y} \right)} \over {{A_6}\left( {x,y} \right)}}} \right| + {B_3}\left( {x,y} \right)\ln \left| {{{{A_1}\left( {x,y} \right)} \over {{A_2}\left( {x,y} \right)}}} \right|} \right)} \hfill \cr }
where A
1 (x, y), A
2 (x, y), A
3 (x, y), A
4 (x, y), A
5 (x, y), A
6 (x, y), B
1 (x, y), B
2 (x, y), B
3 (x, y) are homogeneous polynomials of degree a, a, b, b, c, c, n, n, m respectively. Concrete example exhibiting the applicability of our result is introduced.