English
The induced map kerLift φ is the natural map from G/ker φ to H sending the coset g ker φ to φ(g).
Русский
Индукцированная карта kerLift φ есть естественная карта из G/ker φ в H, отправляющая косет g ker φ в φ(g).
LaTeX
$$$\\kerLift_\\phi(\\overline{g}) = φ(g)$, where \\overline{g} denotes the coset g ker φ.$$
Lean4
/-- The induced map from the quotient by the kernel to the codomain. -/
@[to_additive /-- The induced map from the quotient by the kernel to the codomain. -/
]
def kerLift : G ⧸ ker φ →* H :=
lift _ φ fun _g => mem_ker.mp