Classical and Quantum Solutions and the Problem of Time in $R^2$ Cosmology

We have studied various classical solutions in $R^2$ cosmology. Especially we have obtained general classical solutions in pure $R^2$\ cosmology. Even in the quantum theory, we can solve the Wheeler-DeWitt equation in pure $R^2$
cosmology exactly. Comparing these classical and quantum solutions in $R^2$
cosmology, we have studied the problem of time in general relativity.