This bead is at Row 4. Column 3 has a bead at Row 4 too → red (=).
- Column 4 goes down to Row 4, so use Rule 2: look 1 column back, at Column 3.
- Column 3 has a bead at Row 4 too → red (=).
Common table reading watchout: Thinking "no bead at this row" means blue. It is blue only when Column 3 stopped exactly one row above this bead.