Before revision:  Mathematical tools based on dynamical systems theory are often used to model these networks . The size and complexity of these models , however, mean that their behaviour is not always intuitive and the underlying mechanisms can be difficult to decipher.
After revision:  Mathematical tools based on dynamical systems theory are often used to model these networks , but the size and complexity of these models , however, mean that their behaviour is not always intuitive and the underlying mechanisms can be difficult to decipher.