### Abstract

A hyperset approach to Web-like (semistructured) databases and query language Delta are presented in a simple, intuitive and quite precise way, hopefully for a wider audience, with demonstrating how this abstract view can be represented in concrete terms of set equations allowing cycles. This approach answers the question on how expressive power of querying to semistructured databases can be characterised both in terms of descriptive complexity and by some demonstrating examples such as defining in terms of Delta the formal semantics of path expressions, as well as of other known languages UnQL and UnCAL.