Id_A(x,y) is the type of proofs that x equals y in type A; refl: Id_A(x,x); J-eliminator allows transport along equalities; HoTT gives Id its homotopy interpretation.
Id_A(x,y) is the type of proofs that x equals y in type A; refl: Id_A(x,x); J-eliminator allows transport along equalities; HoTT gives Id its homotopy interpretation.