As a particular example, the Combine Interleaving Gap C step in Figure 1C is obtained from the string abgab.
we define the parsing schema for MG k , a parser for mildly ill-nested structures for gap degree k, as the schema where (1) the item set is like that of WG k , except that items can now contain any mildly ill-nested structures for gap degree k, instead of being restricted to well-nested structures; and (2) the set of deduction steps consists of a Link step as the one in WG k , plus a set of Combine steps obtained as expressed in Figure 1D.