exponentiation - Negative Number raised to fractional power

How would you solve a negative number raised to a fraction a/b if b is odd and a is evem?
Ignoring imaginary numbers

i.e $(-1)^\frac23$ Calculator returns an error

$(-1)^\frac 13 (-1)^\frac 13$ = -1.-1 = 1 (By law of indices)

or

$(-1^\frac13 )^2$ = 1

or

$(-1^2)^\frac13$ = 1

What about for other cases of a and b?