Even continuity and topological equicontinuity in topologized semigroups

A topologized semigroup X having an evenly continuous resp., topologically equicontinuous, family RX of right translations is investigated. It is shown that: (1) every left semitopological semigroup X with an evenly continuous family RX is a topological semigroup, (2) a semitopological group X is a paratopological group if and only if the family RX is evenly continuous and (3) a semitopological group X is a topological group if and only if the family RX is topologically equicontinuous. In particular, we get that for any paratopological group X which is not a topological group, the family RX provides an example of a transitive group of homeomorphisms of X that is evenly continuous and not topologically equicontinuous. The last conclusion answers negatively a question posed by H.L. Royden.