User blog comment:Ytosk/Transfinite Extensions of BMS/@comment-35470197-20190826125522/@comment-35470197-20190927115749

Your TBMS is ill-defined, because you just set the rule to expand an expression whose rightmost row includes as the rightmost entry. For example, the expansion ()(2,1,1,1)[4]=()(2,1,1)(3,2,2,)... is guaranteed by no written rules.