Concept
Tricot — where it appears
The simplest warp-knitted structure, two guide bars lapping in opposite directions. The opposite lapping is what ties the wales together, and a single bar lapping alone gives chains that fall apart into separate strings.
Named by 2 essays across one field — each of them below, with the objects they name alongside it.
Warp knitting, which is a different thing entirely
Every wale has its own thread, and if the thread never leaves its wale the fabric is a set of independent cords. Whether a lapping makes cloth is decided by a coprimality condition — the satin theorem, in a knit.
What a second guide bar is for
One warp-knit bar leaves the wales in as many independent fabrics as its shog shares factors with the width. Two bars leave the greatest common divisor of both — so a pair of shogs that each fail alone can succeed together, and a pair that share a factor cannot.
Named alongside it
The objects these essays reach for when they reach for this one.
LappingWaleWarp knittingCloth integrityConnectivityGreatest common divisor