What do you call a situation or case where a person say we are in a A XOR B situation when it's not?

What do you call a situation or case where a person say we are in a A XOR B situation when it's not? Let's say someone say either A is true or B is true, but not both A and B is true, but it's false. What do you call such a case or situation in philosophy?

• Does this answer your question? What is the name of this fallacy: 101 is either binary or decimal? – Conifold Feb 27 at 14:07
• You need more information. This is NOT enough. All we know is that in this situation we have an exclusive a or b. What that means typically is that both a & b cannot be true simultaneously. However in a scenario like you are describing both a & b MAY BE FALSE simultaneously. We don't have enough information to RULE OUT both a & b are false. You indicate that both a & b cannot be true only.You need more information. This is NOT enough. All we know is that in this situation we have an exclusive a or b. What that means typically is that both a & b cannot be true simultaneously. However in a scena – Logikal Feb 27 at 14:31
• I want to clarify my last comment here since it was incomplete. All we know is that you indicate both cannot be true. If you don't exclude bot a & b are FALSE we don't know if this is a fallacy. Once we know both cannot be true & both cannot be false simultaneously we KNOW this is a fallacy of bifurcation aka the false dilemma. This is an error because there are more than two alternatives as a solution. – Logikal Feb 27 at 15:00