Dynamic Forcing Chain Plus
A Dynamic Forcing Chain Plus applies ordinary deductions inside the temporary state created by one starting assumption. Those deductions can extend the branch, but every result remains conditional on the starting assumption until a contradiction or exhaustive conclusion discharges it.
What is a Dynamic Forcing Chain Plus?
The “Plus” label describes the allowed intermediate deductions, not different truth rules. Each subset, intersection, fish, or wing must satisfy its normal premises in the current assumed state and must preserve the outer assumption in the written proof.
How to spot it
Record the original grid and the branch state separately. When direct propagation stops, check the temporary state for a sound intermediate deduction, apply it only within that state, and continue. Do not transfer an intermediate elimination to the original grid early.
The logic
If the complete assumed state eventually contradicts a Sudoku constraint, reject the starting assumption. If every exhaustive starting alternative reaches the same target conclusion, accept that conclusion. Intermediate deductions supply implications; they do not discharge the assumption themselves.