Logic and set theory ; symbols and concepts 邏輯和集論.符號和概念
Versa also provides facilities - such as full boolean logic and set operations , transitive operations , aggregates , substring matching , and other core data type manipulation - that are lacking in many other rdf query systems Rdf模型是圖形結構,該結構可以非常簡單也可以令人難以置信的復雜。事實上,極端情況下, semantic web的設想是要創建至少同當前web一樣大的rdf模型。