  Recent developments in large language models (LLMs) have shown promise in
their ability to generate synthetic query-document pairs by prompting with as
few as 8 demonstrations. This has enabled building better IR models, especially
for tasks with no training data readily available. Typically, such synthetic
query generation (QGen) approaches condition on an input context (e.g. a text
document) and generate a query relevant to that context, or condition the QGen
model additionally on the relevance label (e.g. relevant vs irrelevant) to
generate queries across relevance buckets. However, we find that such QGen
approaches are sub-optimal as they require the model to reason about the
desired label and the input from a handful of examples. In this work, we
propose to reduce this burden of LLMs by generating queries simultaneously for
different labels. We hypothesize that instead of asking the model to generate,
say, an irrelevant query given an input context, asking the model to generate
an irrelevant query relative to a relevant query is a much simpler task setup
for the model to reason about. Extensive experimentation across seven IR
datasets shows that synthetic queries generated in such a fashion translates to
a better downstream performance, suggesting that the generated queries are
indeed of higher quality.
