# Primary decomposition in one variable not working

The following doesn't work, it yields a `NotImplementedError`

:

```
R.<x> = GF(2)[]
I = R.ideal(x^3+1)
I.primary_decomposition()
```

However, if I introduce a superfluous variable `y`

, it works:

```
R.<x,y> = GF(2)[]
I = R.ideal(x^3+1,y)
I.primary_decomposition()
```

Compare: https://ask.sagemath.org/question/567...

As far as I understood correctly, `PolynomialRing(K)`

is the same as `K[]`

, but `PolynomialRing(K,1)`

is different. Let's try it out, it works:

```
R.<x> = PolynomialRing(GF(2),1)
I = R.ideal(x^3+1)
I.primary_decomposition()
```