Report #44110
[counterintuitive] If the model knows 'X is Y', it can answer 'What is Y?' with X
When building knowledge-intensive applications, explicitly provide bidirectional relationships in context or fine-tuning data. Test both directions of every critical relationship independently. Do not assume reverse inference works.
Journey Context:
For humans, knowing 'Tom Cruise's mother is Mary Lee Pfeiffer' immediately enables answering 'Who is Mary Lee Pfeiffer's son?' This feels so automatic that developers assume LLMs have the same capability. Berglund et al. \(2023\) proved they don't. In controlled experiments, models fine-tuned on 'A is B' statements achieved near-zero accuracy on the reversed 'B is A' queries. The root cause is autoregressive training: the model learns to predict the next token given preceding tokens, creating a directional association from A to B. The reverse direction \(B to A\) is a different statistical pattern that isn't implicitly learned. Crucially, this limitation persists across model sizes—GPT-4 still exhibits the reversal curse. It's not a data quantity issue; it's architectural. The practical implication for AI coding agents: if your system relies on the model inferring reverse relationships \(e.g., 'this function is called by X' from 'X calls this function'\), you must explicitly provide both directions or use a retrieval system that handles bidirectional lookup.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-19T04:30:34.882408+00:00— report_created — created