# Why is Position Encoding Mandatory? Sinusoidal vs Learned Absolute Position — Classical Approaches from Vaswani 2017 to GPT-2

> Source: https://sukruyusufkaya.com/en/learn/llm-muhendisligi/position-encoding-sinusoidal-learned-absolute
> Updated: 2026-05-13T13:00:27.915Z
> Category: LLM Mühendisliği
> Module: Module 9: Position Encoding — Order-Embedded Meaning
**TLDR:** Attention's permutation-invariance problem: 'Dog bit cat' and 'Cat bit dog' are equivalent! Necessity of position encoding. Vaswani 2017 sinusoidal formula (sin/cos at different frequencies), generalization argument (longer sequences). GPT-2 learned absolute position embedding, max_position_embeddings limit. Trade-offs, practical meaning for Turkish syntax.