CM20019---Computation III:
Formal Logic and Semantics
2007
Exercise sheet 3---Solutions
Problem 1
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(1) [X := Y] ;
(2) [X := Y, Y := Z] ;
(3) [X := (X + Y), Y := (X + Y)] .
Problem 2
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s = [X := Y] and t = [Y := X]; we have that s.t = t and t.s = s.
Problem 3
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s = [X := Y, Y := W, Z := X] and t = [Z := Y, W := Z].
Problem 4
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s = [X := Y, Y := Z, Z := X].