I know that the XOR operation of three variables is invariant (symmetric) with respect to two of them. How Can I discover the invariance of any boolean function automatically for all possible variables combinations with sagemath? In the example of the xor operation, I am tried to use the method is_symmetric(), but this method check if the entire function is invariant, and it is not possible to specify as input the variables to check the invariance (symmetric). Here the function
from sage.crypto.boolean_function import BooleanFunction
R1 = BooleanPolynomialRing(3, ','.join(['x','y','z']))
f=BooleanFunction(R1(x*y+z))
