效绵鼎 Derivations -Intuition We derive strings in the language of a CFG by starting with the start symbol,and repeatedly replacing some variable A by the body of one of its productions. That is,the "productions for A"are those that have head A. .10Derivations – Intuition ◼ We derive strings in the language of a CFG by starting with the start symbol, and repeatedly replacing some variable A by the body of one of its productions.  That is, the “productions for A” are those that have head A. 10