In strategic settings, **abstraction** is a way to compress a complex situation into a simpler one without losing what matters for decision-making. The goal is not to remove detail for its own sake, but to represent different situations that lead to the same incentives and choices in the same way.

## Concept compression
Good abstractions bundle together situations that are effectively the same from a strategic point of view. Instead of tracking every micro-detail, you keep the signals that actually change behavior.

- Focus on the information that moves decisions.
- Remove incidental detail that does not change incentives.
- Keep the representation small enough to reason about quickly.

## Strategic equivalence
Two situations are **strategically equivalent** if, despite surface differences, the best responses and trade-offs are the same. Treating them as a single case makes reasoning faster and clearer without changing the conclusions.

- Equivalent incentives → equivalent representation.
- Same best responses → same strategic class.
- Different look, same decisions.

## Why it helps
- **Speed**: Smaller representations are faster to analyze.
- **Clarity**: Highlights the drivers of behavior.
- **Generalization**: One solution applies to many equivalent situations.

## Abstraction and equilibrium
Compression trades some exactness for speed. An equilibrium computed on an abstract model is an approximation to the equilibrium of the full setting. It is exact when the abstraction preserves strategic equivalence. Otherwise it is a useful approximation for planning and search.

Abstraction, done well, is disciplined compression: preserve the parts that shape choices and compress the rest.

## See also
- [What is an Equilibrium?](/docs/what-is-an-equilibrium)
- [What is Thinking?](/docs/what-is-thinking)