7b53 wrote:say from a bivalve cell of x,y (r1c1)

if we start the chain with x , and somehow (r1c9) end up to be digit z

then we can say r1c9<>y

so the logic goes....

when r1c1=x =>r1c9=z => r1c9<>y

when r1c1=Y =>r1c9<>y

just wondering if this related to xy-chain ?

If a chain is comprised 100% of bivalued cells, it is an xy-chain. If comprised 100% of bilocal strong inferences (links), i.e., with two grouped or ungrouped like-candidates in a row, column or box, then it might be called a bilocal chain. A mix of bivalues and bilocals is a mixed chain, or simply a chain.

I'd recommend forgetting, at least for now, the Sudoku Explainer terminology mentioned by

champagne. Dynamic, dynamic+, and nested forcing chains are really "networks" instead of chains, are needed only in puzzles beyond the capability of most human solvers, and are terms not generally used on this forum.