Exercise 4.1
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3.
KRIS cannot answer with T because the system only knows, that GRETE is a PERSON. If KRIS should answer with T, one has to change to rule (assertion GRETE PERSON) into:
(assertion GRETE WOMAN)

4.
KRIS knows nothing about EMIL but that EMIL is the husband of CHRISTA. If KRIS should answer with T, there has to be one more rule which says:
(assertion Emil DEAD)