"Lion and Man": Upper and Lower Bounds

Given a lion and a man, their initial positions, and restrictions on their ranges and speeds, how quickly can the lion get within a given distance from the man? We consider the case in which the lion and man are restricted to the interior of a circle and each is limited to the same speed. INFORMS Journal on Computing , ISSN 1091-9856, was published as ORSA Journal on Computing from 1989 to 1995 under ISSN 0899-1499.