Counting independent sets and colorings on random regular bipartite graphs

We give a fully polynomial-time approximation scheme (FPTAS) to count the number of independent sets on almost every $\mathrm{\Delta }$-regular bipartite graph if $\mathrm{\Delta }\ge 53$. In the weighted case, for all sufficiently large integers $\mathrm{\Delta }$ and weight parameters $\lambda =\tilde{\mathrm{\Omega }}\left(\frac{1}{\mathrm{\Delta }}\right)$, we also obtain an FPTAS on almost every $\mathrm{\Delta }$-regular bipartite graph. Our technique is based on the recent work of Jenssen, Keevash and Perkins (SODA, 2019) and we also apply it to confirm an open question raised there: For all $q\ge 3$ and sufficiently large integers $\mathrm{\Delta }=\mathrm{\Delta }(q)$, there is an FPTAS to count the number of $q$-colorings on almost every $\mathrm{\Delta }$-regular bipartite graph.