We prove that a saturated weakly branch group G has the property R∞
(any automorphism ϕ:G→G has infinite Reidemeister number) in each of
the following cases:
- any element of Out(G) has finite order;
- for any ϕ the number of orbits on levels of the tree automorphism t
inducing ϕ is uniformly bounded and G is weakly stabilizer transitive;
- G is finitely generated, prime-branching, and weakly stabilizer
transitive with some non-abelian stabilizers (with no restrictions on
automorphisms).
Some related facts and generalizations are proved.