Equation 7 · Part 1 · Retrieval Is an Evidence System, Not a Memory
Symbol z
What this part means
z is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Its job in the formula
z is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol z→Article meaning
The passage around this formula
Read the structure rather than the arithmetic. The generator is never conditioned on the corpus. It is conditioned on z — one span, or a handful — and its output distribution is a weighted account of what those spans support. Everything outside has probability zero of influencing the answer, and the system has no representation of what it excluded. REALM made the same commitment on the training side, learning a latent retriever end-to-end so that the model attends over documents drawn from a corpus at pretraining, fine-tuning and inference time, and reporting 4–16% absolute gains on open-domain question answering over prior methods [ 2 ] .
Learn the underlying idea
A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
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Sources cited in the surrounding passage
These citations provide research context; check each source for the exact claim it supports.