In UCG gardens — as with data structure and algorithm design — there are trade-offs among retrieval difficulty (friction, for humans; time complexity, for machi

In UCG gardens — as with data structure and algorithm design — there are trade-offs among retrieval difficulty (friction, for humans; time complexity, for machines), update difficulty, centralization and skill set of contributors, and centralization and skill set of editors, and the complexity of the structures themselves. IMDB, CYC, Wolfram, and various RDF data sets, sample this space differently, and have different amounts of data and richness, probably as a result.