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M.S. by Research — neural information retrieval

Teaching a retriever what a bug report is really about

IIIT Hyderabad · May 2016 — Aug 2018

Dense retrieval for short, noisy documents: a BERT model trained with triplet learning and inter-document context, and a screening system that saved a third of reviewer time at full recall.

BERTPyTorchDense RetrievalTriplet LearningThesis page
screening time saved at 100% recall

31%

screening time saved at 100% recall

Recall@1 across three corpora

61–65%

Recall@1 across three corpora

recall improvement over baselines

10–15%

recall improvement over baselines

The problem

Short documents — bug reports, abstracts — give a retriever almost nothing to work with. Lexical overlap is thin and often misleading, because the words that repeat are the generic ones.

In systematic review screening, recall is not negotiable. A system that misses one relevant paper is not a faster system; it is a wrong one.

Duplicate bug detection has the same shape: near-identical reports use entirely different vocabulary, and the signal lives in what surrounds a report rather than in the report alone.

Constraints that shaped it

  • 100% recall is the floor for the screening system. Time saved is the only variable.
  • Evaluation across three independent corpora — Mozilla, Eclipse, NetBeans — to make sure the gain was not one project's quirk.

Architecture

Corpusreports / abstracts117K+ docsInter-document contextTriplet traininganchor / pos / negBERT encoderDense indexRanked results61–65% R@1

Select any box for the design decision behind it.

Triplet training on the left, retrieval and reranking on the right.

What I owned

  • 01The full thesis: problem formulation, model, training regime, and evaluation.
  • 02NITBUG — the BERT-based dense retrieval model with triplet learning and inter-document context.
  • 03The PubMed screening system evaluated at 100% recall.

What I would do differently

Everything I do now with RAG is this problem wearing different clothes. Retrieval quality sets the ceiling; the generator only decides how close you get to it. Eight years later that is still the part teams under-invest in.