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A binding is a pair (make-binding s v) where s is a symbol (a variable) and v is a boolean value (an element of { true, false }.
An environment is a (list-oof of binding).
When the eval function encounters a variable (symbol), it looks up the symbol in the environment and replaces the symbol it's boolean value if it exists.
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Use the following set of reduction rules to perform this conversion
| Code Block |
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(make-If X false true) => (make-Not X) |
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(make-If X Y false) => (make-And X Y) |
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(make-If X true Y) => (make-Or X Y) |
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(make-If X Y true) => (make-Implies X Y) |
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where X , Y , and Z are arbitrary If forms. This set of rules is Church-Rosser, so the rules can safely be applied using simple structural recursion.