How to correct the prolog full stop in clause body error?

Question

weather(phoenix, spring, hot).

weather(phoenix, summer, hot).

weather(phoenix, fall, hot).

weather(phoenix, winter, warm).

weather(wellington, spring, warm).

weather(wellington, summer, warm).

weather(wellington, fall, hot).

weather(wellington, winter, cold).

weather(toronto, spring, cold).

weather(toronto, summer, hot).

weather(toronto, fall, cold).

weather(toronto, winter, cold).

warmer_than(C1, C2) :-

weather(C1, spring, hot),

weather(C2, spring, warm).

colder_than(C1, C2) :-

weather(C1, winter, cold),

weather(C2, winter, warm).

weatherquestions :-

warmer_than(phoenix, X),

write('Phoenix is warmer than '), write(X), nl.

colder_than(X, toronto),

write('Toronto is colder than '), write(X), nl.

warmer_than(X, wellington),

write('The city/cities warmer than Wellington are '), write(X), nl.

colder_than(X, phoenix),

write('The city/cities colder than Phoenix are '), write(X), nl.

colder_than(X, toronto),

warmer_than(X, wellington),

write('The city/cities colder than Toronto and warmer than Wellington are '), write(X), nl.

print_all_warmer_than(X) :-

warmer_than(X, phoenix),

write('The cities warmer than Phoenix are '), write(X), nl.

Answer 1

In your weatherquestions rule, you have periods instead of commas after the nl's (newlines). I am not sure if that is what you meant by your question, but that is one issue that I see with your Prolog code.