**random_subseq**(

`+List, -Subseq, -Complement`)

**random_subseq**(

`-List, +Subseq, +Complement`)

`Subseq`of

`List`, with

`Complement`containing all elements of

`List`that were not selected. Each element of

`List`is included with equal probability in either

`Subseq`or

`Complement`.

random_subseq/3
may also be called with `Subseq` and `Complement`
bound and `List` unbound, which will recreate `List`
by randomly interleaving
`Subseq` and `Complement`. This mode may fail
randomly, matching SICStus behavior. The failure probability corresponds
to the probability of the "forward" mode selecting a `Subseq`/`Complement`
combination with different lengths.

- Compatibility
- SICStus 4