AIC

Alternating Inference Chain (AIC) is a powerful chain technique that links candidates through alternating strong and weak inferences, potentially spanning multiple digits. When a chain forms a loop or returns to its start, eliminations or placements follow.

Technique

1. Build a chain alternating strong links (conjugate pairs or bivalue cells) and weak links (shared houses).
2. Type 1 (Continuous Loop): All cells in the chain form an even loop, allowing eliminations from cells seeing both ends of any strong link.
3. Type 2 (Same cell, different digits): Both endpoints reach the same cell with different digits on strong links; all other candidates are eliminated from that cell.
4. Type 3 (Discontinuous): Both endpoints have the same digit on strong links pointing at the same cell; that digit is eliminated from the start cell.

Tips

• AIC generalizes many simpler techniques: X-Chains, XY-Chains, and remote pairs are all special cases.
• Strong links can be within a house (conjugate pair) or within a cell (bivalue).
• Practice with shorter chains before attempting longer ones.