Cell Forcing Chains
Try each candidate of one cell in turn, follow the chain from each, and keep only what every branch agrees on.
All candidates have been entered in the empty cells.
At least one candidate in A is true. On a solid link, one false end makes the other end true. On a dashed link, one true end makes the other end false. Apply these rules in link order in each branch. All 3 branches reject the same candidate. Candidate 3 can be removed for every possible A.