Before revision:  We find that for arbitrary functional form of the volatility, \sigma(y), the (1 + 2) evolution equation admits always two Lie symmetries, plus the linear symmetry and the infinity number of solution symmetries.
After revision:  We find that for arbitrary functional form of the volatility, \sigma(y), the (1 + 2) evolution equation admits always two Lie symmetries, plus the linear symmetry and the infinite number of solution symmetries.