CW filtration
= CW filtration
{c}
A CW filtration builds a CW complex by its skeleta
$$
\varnothing=X^{-1}\subset X^0\subset X^1\subset\cdots,
$$
where each quotient $X^n/X^{n-1}$ is a wedge of $n$-spheres, one for each $n$-cell.
= CW filtration
{c}
A CW filtration builds a CW complex by its skeleta
$$
\varnothing=X^{-1}\subset X^0\subset X^1\subset\cdots,
$$
where each quotient $X^n/X^{n-1}$ is a wedge of $n$-spheres, one for each $n$-cell.