Samsung Electronics Co., after a series of setbacks in developing the type of memory chips crucial for the artificial intelligence market, is beginning to make progress in narrowing the gap with rival SK Hynix Inc. Samsung has made important headway in its comeback, including winning the long-awaited approval from AI giant Nvidia Corp. for a version of its high-bandwidth memory chips called HBM3, according to people familiar with the matter. It also anticipates approval for the next generation, ...