reduction VariableRule1a:
	x*a + x*b -> (a + b) * x
reduction VariableRule1b:
	x*a - x*b -> (a - b) * x
reduction VariableRule1c:
	a*x + b*x -> (a + b) * x
reduction VariableRule1d:
	a*x - b*x -> (a - b) * x

reduction VariableRule2a:
	a*x + x -> (a + 1) * x
reduction VariableRule2b:
	a*x - x -> (a - 1) * x

reduction VariableRule3a:
	x + a*x -> (1 + a) * x
reduction VariableRule3b:
	x - a*x -> (1 - a) * x