The logical fallacy of false conversion / illicit conversion occurs when the terms of a premise are switched in the conclusion when the premise uses the word all of some/not.

"All S are P. Therefore, all P are S.

No S are P. Therefore, no P are S.

Some S are P. Therefore, some P are S."

"All S are P. Therefore, all P are S." (invalid form)

"All trucks are vehicles. Therefore, all vehicles are trucks." (invalid form)

"Some S are not P. Therefore, some P are not S." (invalid form)

"Some vehicles are not trucks. Therefore, some trucks are not vehicles." (invalid form)

"No S are P. Therefore, no P are S." (valid form)

"No trucks are sports cars. Therefore, no sports cars are trucks." (valid form)

"Some S are P. Therefore, some P are S." (valid form)

"Some men are short people. Therefore, some short people are men." (valid form)