| ICALP'97: Accepted Papers |

| | We prove that the recognizable series are certain rational power series, which can be constructed from the **polynomials** by using the operations sum, product and a restricted star which is applied only to series for which the elements in the support all have the same connected alphabet. |

| | The testers in the latter have the goal of determining whether a program computes a **polynomial** of given degree, whereas we are interested in checking the properties of a given **polynomial**. |

| | All current **polynomial** time methods (to our knowledge) are unlikely to recover the topology of the true tree from sequences of realistic lengths (bounded, perhaps, by 10,000 nucleotides) for large sets of widely divergent sequences, even if such methods are known to be able to reconstruct the correct topology given long enough sequences. |

| www.cs.unibo.it /icalp/AccptAbstr.html (9507 words) |