In the algebraic group model (https://eprint.iacr.org/2017/620.pdf), can one use "if" statement? For example, can one do the following in AGM?

input: x, y, z

if (x = y) then z = x else z = xy

...

If this is allowed in AGM, how can we represent the output as x^a y^b z^c, where a, b, c are fixed integers?