Lecture 10 Notes

We sometimes call this a context argument or

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Unformatted text preview: §  subst If the list is empty, there are no occurrences of            !! ¦ § £ ¥ ¥     !¥! ¤ 2 ¡ § 5!  4      ©¨¥ ¤ ¡§ £¡ £ 4 ¡  !¢   ! ¥   ¥   ¡ 4 §     subst Let us first work on . The grammar tells us there should be two alternatives: £    ¡§   ¤ ¢©¨¥ ¢    Now we can move on to . From the grammar, we know that the symbol expression is either a symbol or an s-list. If it is a symbol, we need to ask whether it is the same as the symbol . If it is, the answer is ; if it is some other symbol, the answer is the same as . If is an s-list, then we can recur using to find the answer. 2¡§ £ £ ¡ ¤  ¡ ¤  £ ¤ £ ¡ ¤      £  ! ¡   ¡ ¡   !  ¤ 2 ©§  ¡ ¡  ¤ ¡¤ 2 ¡ §  ¤ ¤  9§¨¡   ¡ ¨§  !   ¥4  ¡  ¤  ¤  ¤ 2 ¡ § ¡  §¥ ¤ ¡ ©©¨©¢  £ 4 4  ¤ ¡  £ £ £ £ £ subst-in-s-exp £       £¥    £¥    4 5!...
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This document was uploaded on 03/17/2014 for the course CSG 111 at Northeastern.

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