User blog comment:DrCeasium/HAN: multidimensional arrays/@comment-11227630-20131021050013

How to use the main rule R1 in w/ chains? I mean,

[1]w/[1,2,2]w/[1,3]=[1]w/[1,A,2]w/[1,3], but what's the A here?

Is A [1]w/[1,1,2]w/[1,3], or [1,1,2]w/[1,3], or [1]w/[1,1,2], or only [1,1,2] ?