()

+a

- +a -> b %[stops at -]%

a*b

a-> -b

-(a->b)

a-> b * c

(+a * (-b)+ * d) -> e %[nested variance]%

a->(b->c+)

a->(b->c)+

(a-> +b)->c

(a-> +b) * d ->c

(+a,b) -> c

a*b->c

+a * -b -> c

a*b->c*d->e

(a*b)->c

(+a * (-b *c)+ * d) -> e %[nested products]%

(-a * (+b ->c)- * -d) -> e %[nested products]%

(-a * (+b ->c)- * -d) -> e %[nested products]%

(a,b) * (c,d) -> (e,f) %[Intersection]%

(a,b) %[Intersection]%

(a,b->c)