Substitution / promotion issues

[pzinn]

There are still a few issues with substitution/promotion that I want to take care of. Here's one (well, two, actually):

i1 : R=QQ[x]
   
o1 = R

o1 : PolynomialRing

i2 : sub(x/(x+1),x=>x+1) -- rejects

stdio:3:4:(3): error: expected x to be a generator of frac R

i3 :  sub(x/(x+1),x_(frac R)=>x+1) -- accepts but wrong target therefore wrong result

o3 = 1

o3 : R

I might add some more in this thread.

[pzinn]

here's another one:

i1 : R=QQ[t]

o1 = R

o1 : PolynomialRing

i2 : t*matrix{{1}}
stdio:2:2:(3): error: no method found for applying promote to:
     argument 1 :  t (of class R)
     argument 2 :  ZZ