Question

5. Let U be a universe of persons and let ParentOf, MotherOf, FatherOf, DaughterOf, and SonOf be relations over U such that ParentOf(r, y) if r is a parent of y, MotherOf (r,y) if r is the mother of y, FatherOf (r,y) if r is the father of y, DaughterOf(x,y) if r is the daughter of y, and SonOf(x,y) if x is the son of y, respectively.

Answer 1

Solution:

The expression is given below:

$p(x, y)= \forall x \forall y[\exists z \exists w[parent(z, x) \&\ parent(w, y)]]$

There can be more than one ways to write the expression as well.

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