The problem of on-line bin packing restricted to instances with only two item sizes (known in advance) has a well-known lower bound of 4/3 for its asymptotic competitive ratio. We present an algorithm which shows that this lower bound is also an upper bound. Hence the asymptotic competitive ratio for this on-line problem is equal to 4/3. Our result extends the corresponding result of Faigle, Kern and Turan (1989) for item sizes restricted to 1 2 - and 1 2 + for any fixed nonnegative < 1 6 .
Gregory Gutin, Tommy R. Jensen, Anders Yeo