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The diagrams are indeed hypergraphs. They are taken from Chapter 12 of the book, and are simplifications of Figures 12.44 and 12.45. The solid lines enclose rel
by david-maier 8y ago
The diagrams are indeed hypergraphs. They are taken from Chapter 12 of the book, and are simplifications of Figures 12.44 and 12.45. The solid lines enclose relation schemes, and the dotted line represent "objects", which here signify groups of relations it makes sense to join. There's a scan of the text at http://web.cecs.pdx.edu/~maier/TheoryBook/TRD.html http://web.cecs.pdx.edu/~maier/TheoryBook/TRD.html if you want to look at the figure originals.
- dragontamer 8y agoGood eye! They look precisely like figure 12.44 and 12.45!
- Scarbutt 8y agoHe's the author of the book ;) (or someone stole his name)
- dragontamer 8y agoWoops. I guess I should read usernames more carefully from now on.
- david-maier 8y agoYup, I'm the author. As I recall, I didn't have much input on the cover. Whoever did the design must have liked the look of the figures. However, as you see, they're pretty hard to interpret with the attribute names removed.
- jesuslop 8y agoGallo et al. expressed functional dependencies via them here https://www.sciencedirect.com/science/article/pii/0166218X9390045P https://www.sciencedirect.com/science/article/pii/0166218X93...