Solve the following problem (i. e. the first attribute grammar may accept what the second attribute grammar rejects and vice versa): Augment this grammar with attributes, attribute computation functions, and predicates to reject WAE expressions which contain WITH sub-expressions with duplicate variable names in their alist. For example, the following WAE expression should be rejected:

{ +20 { with { x 2} {y 4} {x 5}} {+ x y}}}

there is no universally accepted definition of art. although commonly used to describe something of beauty, or a skill which produces an aesthetic result, there is no clear line in principle between (say) a unique piece of handmade sculpture, and a mass-produced but visually attractive item. we might say that art requires thought - some kind of creative impulse - but this raises more questions: for example, how much thought is required? if someone flings paint at a canvas, hoping by this action to create a work of art, does the result automatically constitute art?

leaning back,   no eye contact,   fidgeting in the seat