I have worked on all things in symbolic logic since 1962 but I have never seen the connective ▼.Can somebody help me with the elementary logic, please. I need to prove the validity of the argument. Thank you!
1. A → (B ▼ C)
2. E → (C ▼ P)
3. ~C
/∴ ~(B ▼ P) → ~(A ▼ E