A query system in a biological database

We present a query system that has been implemented in a practical biological database-GPCRDB. Distinguishing features of this system include: smart query relaxation and smooth integration of navigation with conventional language based query functions. Query relaxation is required due to the fact that queries are not always effective (in other words, expected results are frequently not achieved), particularly in scientific databases like biological databases, in which complex domain knowledge is heavily used. On the other hand, navigation capability is desired as complex data sets are involved, especially in a WWW based environment where multiple hyperlinks are often employed. For efficient implementation, the "fuzzy equivalence class" concept has been applied that captures an important type of domain knowledge.