Περίληψη. We demonstrate KnowDS, a system that extends Data Spaces with semantic search capabilities. We show how KnowDS can leverage the minimal descriptive metadata of the data assets in a Data Space to construct a relevance graph, and how it uses Steiner trees to find relevant items that do not contain any of the query terms. We describe the KnowDS system in detail, and present a running example that showcases its functionality.