SAT-SOLVING-EXAMPREP/Proofs.md

• used to verify UNSAT results
• Idea is to derive empty clause

RUP

• Reverse Unit Propagation
• Proofs only by [Unit propagation](SAT_in_general#Special Case Unit Resolution)

RAT

• Reverse Asymmetric Tautology
• Idea: If all Resolutions end in Tautologies (or tautology by RUP) clause can be removed
• Supports more than just [UP](SAT_in_general#Special Case Unit Resolution)
• Way to represent [Blocked Clause removal](Preprocessing_Inprocessing#Blocked Clauses / Blocked literal)
  • Replace need for tautology with RUP condition

Redundancy

• A clause in a Formula is redundant
  • Simplifying F by setting C to false implies any Formula simplified by another assignment
  • F_\alpha \models F_\omega , where \omega satisfies C
• The idea of Propagation Redundancy (PR) is more general even than RAT