10 We carried out timing experiments on the best A* parsers for each model (SX and NULL for PCFG and HWDep, respectively), comparing them with our CKY implementation and the agenda-based CKY simulation EXH; we used the same data as in §3.2.
pruning means approximate search: if a lexical category used by the highest probability derivation is pruned, the parser will not find that derivation ( §2).