This is the first draft of a book about higher categories approached by
iterating Segal's method, as in Tamsamani's definition of n-nerve and
Pelissier's thesis. If M is a tractable left proper cartesian model category,
we construct a tractable left proper cartesian model structure on the category
of M-precategories. The procedure can then be iterated, leading to model
categories of (β,n)-categories