Proposed Proof Checkers

We received the following proposals for proof checkers for the international SAT competitions.

• Verified LRAT and LPR Proof Checking with cake_lpr
  by Yong Kiam Tan, Marijn J. H. Heule, and Magnus O. Myreen
• GRAT: a formally verified (UN)SAT proof checker
  by Peter Lammich
• VeriPB and CakePB: Verified Pseudo-Boolean Proofs
  by Bart Bogaerts, Ciaran McCreesh, Magnus O. Myreen, Jakob Nordström, Andy Oertel, and Yong Kiam Tan