Progress around the Boone-Higman conjecture
Progress around the Boone-Higman conjecture
The Boone-Higman conjecture (1973) predicts that a finitely generated group has solvable word problem if and only if it embeds in a finitely presented simple group. The "if" direction is true and easy, but the "only if" direction has been open for over 50 years. In this talk I will discuss an interesting sufficient condition for a group to satisfy the conjecture, which does not require one to care about simple groups, but rather to care about group actions with certain properties. This viewpoint has led to a number of recent breakthroughs on the conjecture, such as proving it for all hyperbolic groups, and for the groups Aut(Fn). In all these cases the simple groups that arise are certain groups of Cantor space homeomorphisms with interesting dynamics, called "twisted Brin-Thompson groups". This talk will touch on joint work with combinations of Jim Belk, Collin Bleak, Francesco Fournier-Facio, James Hyde, and Francesco Matucci.