Final answer:
In a patrilineal society, it would NOT be considered incest if you married your half-sister from your father's other marriage.
Step-by-step explanation:
In a patrilineal society, if your father remarries and has a daughter from this other marriage, it would NOT be considered incest if you married this half-sister. The reason is that incest is generally defined as sexual relations between close blood relatives, such as parents and offspring. While a half-sister shares one biological parent, which would be your father in this case, the social and cultural norms of patrilineal societies typically do not consider this relationship as close enough to be considered incestuous.