Let $K$ $K$ be a link of Conway’s normal form $C (m)$ $C (m)$ , $m \geq 0$ $m \geq 0$ , or $C (m, n)$ $C (m, n)$ with $m n > 0$ $m n > 0$ , and let $D$ $D$ be a trigonal diagram of $K .$ $K .$ We show that it is possible to transform $D$ $D$ into an alternating trigonal diagram, so that all intermediate diagrams remain trigonal, and the number of crossings never increases.

Keywords:

AMSC: 14H50, 57M25, 11A55, 14P99

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