Facts: Pavlatrex is a drug that helps a small percentage of migraine sufferers find relief but only when taken in conjunction with Havlatrex. John suffers from migraines and is currently taking only Havlatrex and Davlatrex, but they are not helping. Conclusion: Pavlatrex will work for John. Necessarily true Probably, but not necessarily, true cannot be determined Probably, but not necessarily, false Necessarily false