## 5.6 Watching Domains

`watch.min`

  > > `{FD.watch.min` `*D1``` `+D2``` `?B``}`

  Returns `true` when and `false` when is entailed by the constraint store.

`watch.max`

  > > `{FD.watch.max` `*D1``` `+D2``` `?B``}`

  Returns `true` when and `false` when is entailed by the constraint store.

`watch.size`

  > > `{FD.watch.size` `*D1``` `+D2``` `?B``}`

  Returns `true` when the size of the domain of `D1` becomes smaller than `D2`.