1. The context-free part of our language can be described by:

expr -> expr plus term

expr -> expr minus term

expr -> term

term -> term mult factor

term -> term div factor

term -> factor

factor -> identifier

factor -> integer

factor -> openpar expr closepar

openpar -> (

closepar -> )

mult ->*

div ->/

plus ->+

minus ->-

integer ->d (d is {0, . . . , 9})

integer -> integer d (d is {0, . . . , 9})

identifier ->c (c is{a, . . . , z})

identifier ->c identifier (c is {a, . . . , z})

The start symbol is expr

Write the derivation with steps: (no need for the parse tree)

expr -> -> bc + 43 * (a+9)