Consider the following vocabulary:

Person$($name$)$: Predicate. Represents a person with the given name.

Location$($place$)$: Predicate. Represents a location or place.

Activity$($activity$)$: Predicate. Denotes various activities.

Friend$($p$1,$ p$2)$: Predicate. Signifies that person p$1$ is a friend of person p$2.$

Visited$($p$,$ l$)$: Predicate. Indicates that a person has visited a location.

$,$ Lives$($p$,$ l$)$: Predicate. Indicates that a person lives in a location.

Enjoys$($p$,$ a$)$: Predicate. Indicates that a person enjoys an activity.

Write the following assertions in first$-$order logic:

a$)$ For all people, there is a location that they have visited.

b$)$ There is a location that nobody has visited.

c$)$ Alice has a friend who enjoys picnics.

d$)$ There is a person who is not a friend of anyone.

e$)$ For each location, there exists a person who has visited it$.$

f$)$ Define a predicate for housemate, Housemate$($p$1,$ p$2),$ that is defined

as two different persons who are living in the same place.

g$)$ Everyone is enjoying an activity.