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Editorial primer

Identity is a space of paths

A short orientation to identity types, groupoid structure, and the distinction between equality and judgmental computation.

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Equality with structure

An inhabitant $p : x =_A y$ witnesses an identification between two terms. Identity elimination supplies composition and inverses up to higher identifications; these laws need not hold judgmentally.

The resulting hierarchy motivates a groupoid interpretation of types: objects are terms, morphisms are identifications, and higher morphisms witness coherence.

The universe matters

Univalence identifies equivalences with paths in a universe, through the statement $(A \simeq B) \simeq (A =_{\mathcal{U}} B)$. It does not make every judgmental equality decidable or erase the distinction between syntax and semantics.

For a complete treatment, consult The HoTT Book, especially its chapters on identity types and univalence.

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This original editorial primer is an orientation, not a peer-reviewed research claim.

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