English
Projections from a family of modules form a coherent system with Pi, yielding canonical identifications.
Русский
Проекции из семейства модулей образуют когерентную систему с Pi, образуя канонические соответствия.
LaTeX
$$proj and pi coherence$$
Lean4
/-- The projections from a family of modules are linear maps.
Note: this definition would be called `Pi.evalLinearMap` if we followed the pattern established by
`Pi.evalAddHom`, `Pi.evalMonoidHom`, `Pi.evalRingHom`, ... -/
def proj (i : ι) : ((i : ι) → φ i) →ₗ[R] φ i
where
toFun := Function.eval i
map_add' _ _ := rfl
map_smul' _ _ := rfl