HoDoKu ALS-XZ Double Linked

The two Almost Locked Sets (ALSs):

     (a) {0}
     (b) {1}
    
share the Restricted Common Candidate (RCC) X = {2}
and another (non-restricted) common candidate Z = {3}.

Because these two ALSs are Double Linked (have two RC values) all common values may be eliminated from any cells which see all instances of that value in both ALSs. Note that these eliminations are in addition to the normal eliminations on the Z value (if any).

The logic is that one of the RC values must be one of the ALSs, so the second RC is pushed into the other ALS, and so on for each additional common value; regardless of weather or not it's in the overlap of the two ALSs (ie regardless of weather or not it's an RCC or just a "CC"). Therefore cells which see all occurrences of each common value in both ALSs cannot be that value.

Therefore we can remove {4}.

{5}