What the Paper Actually Demonstrated

The Transformer’s architecture makes a claim about how sequence computation should be organized, but an architecture becomes evidence only through a specified experiment. This chapter examines what Attention Is All You Need actually measured: the data and training conditions behind its translation results, the paper’s reported comparison with earlier systems, and the additional evidence from parsing, ablations, and attention visualizations. The aim is to separate a measured outcome from the broader conclusion someone might be tempted to draw from it.

That separation is especially important here because the paper combines several kinds of evidence. Translation benchmarks test output quality and estimated training cost under particular data and hardware conditions. Parsing tests whether the same broad design can work on a different sequence task. Ablations test whether selected components matter within one model family. Visualizations offer qualitative clues about what learned attention patterns may represent. These forms of evidence answer related questions, but they do not carry the same strength or scope.

Translation results belong to their conditions

The translation experiments use two WMT 2014 tasks with different data regimes. The English–German dataset contains about 4.5 million sentence pairs and uses byte-pair encoding with a shared source–target vocabulary of about 37,000 tokens. The English–French dataset is much larger, with 36 million sentences and a 32,000-word-piece vocabulary. This difference matters before any score is read: the two language directions do not provide the same amount of training data or exactly the same tokenization setup.

The paper groups sentence pairs by approximate sequence length and forms batches containing roughly 25,000 source tokens and 25,000 target tokens. The models are trained on one machine with eight NVIDIA P100 GPUs. The base models run for 100,000 steps, taking about 12 hours, while the larger models run for 300,000 steps, taking about 3.5 days. The training recipe uses Adam with the paper’s stated coefficients, a learning-rate warmup of 4,000 steps followed by an inverse-square-root schedule, dropout, and label smoothing. These are not incidental settings when the claim includes both quality and training time. They are part of the conditions that produced the reported outcome.

Evaluation also includes choices that shape the result. The authors average several recent checkpoints, use beam search, apply a length penalty, and set an output-length limit while allowing early termination. Those decisions do not invalidate the comparison; they identify what was compared. A claim such as “the Transformer trained faster” should therefore be read as shorthand for “the described configuration, trained with this regime and evaluated under these settings, achieved the reported result in the paper’s comparison.”

The clearest result is on English–German. The larger Transformer reports 28.4 BLEU and the paper says this exceeds the best previously reported models, including ensembles, by more than two BLEU points.