3 Skyscrapers
3 Skyscrapers uses three single-digit strong-link nodes connected by valid weak inferences. The candidate propositions and links define the deduction; a count of highlighted cells or a familiar drawing does not.
What is 3 Skyscrapers?
A representative open sequence is (A=B)-(C=D)-(E=F). Each equals sign marks the page’s exactly-one strong node and each dash a not-both weak inference. The open chain proves an inclusive OR relation between its endpoints.
How to spot it
Choose one digit, list three conjugate or otherwise justified strong nodes, and verify both weak connections. Identify the two far endpoints and require any target to see both.
The logic
Starting with A false forces B true, C false, D true, E false, and F true. Therefore A or F is true, possibly both, and a same-digit candidate seeing both can be removed.