The half-pin, a concept dating back to the 19th century, remains a persistent problem in chess. The basic concept can be seen in real games as well, although we usually call it X-Ray (TODO: article link) combined with an absolute pin.
This theme involves two black pieces positioned on a line between the black king and a long-range white piece. When either of the black pieces moves away from the line, the remaining piece becomes completely pinned. White takes advantage of this immobility to deliver a pin-mate, meaning a checkmate that relies on the pin of one of the defending pieces. A complete half-pin requires the pinning of each of the two black pieces in succession, creating a reciprocal effect that harmoniously links the variations.
Check out a great example, composed by Ake Hesselgren in 1932. The position features three different half-pins (rooks, bishops, and knights), and each of them contains two options to solve the problem with a help of a pinned piece. As a bonus, “normal” checkmates are possible as well: