... Collins and Brooks, 1995; Chelba and Jelinek, 1998). 457 lows (Harrison, 1978; Hopcroft and Ullman, 1979). A context-free grammar (CFG) is a tuple G = (VN, VT, P, S), where VN and VT are ... entire grammar H. To generate, we ex- pand the start word $ E VT into xSy for some (x, y) E L(H$), and then recursively expand the words in strings x and y. More formally, given H, we simultaneously ... of Zr and q~ E 5a(q, b, -~), then Ha can move from state q to state q~, matching symbol b and removing it from the left end of Zr. Symmetrically, if b is the rightmost symbol of zl and ql...