I wonder if it would help to explicitly insert this info into an embedding vector, similar to how we encode word position info. For example, allocate the first 20 vector elements to represent ASCII codes of token's characters (in some normalized way).
I took Qwen3 1.7B model and did the same but rather then using embedding vector I used vector after 1st/etc layer, below accuracies for 1st positions:
- embeddings: 0.855
- 1st: 0.913
- 2nd: 0.870
- 3rd: 0.671
- 16th: 0.676
- 20th: 0.683
And now mega bonus content: the same but with prefix "count letters in ":
- 1st: 0.922
- 2nd: 0.924
- 3rd: 0.920
- 16th: 0.877
- 20th: 0.895
And for 2nd letter:
- embeddings: 0.686
- 1st: 0.679
- 2nd: 0.682
- 3rd: 0.674
- 16th: 0.572
But to be frank I don’t think it’s really needed, I bet everything really needed model learns by itself. If I had time I would’ve tried it though :)
Bonus content, accuracies for other models (notice DeepSeek!):
- Qwen3-32B: 0.873 / 0.585 / 0.467
- Qwen3-235B-A22B: 0.857 / 0.607 / 0.502
- DeepSeek-V3: 0.869 / 0.738 / 0.624