Definition 20 [03S4] Original official author HTML, exact retained edition. Historical TeX conversion verdicts remain unchanged. Cited-edition alignment and mathematical self-containment are not assessed.
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Definition 20
We define compositions m k , k ≥ 2 m_{k},k\geq 2 by the formula
m k ( [ y 0 ] , … , [ y k − 1 ] ) = ∑ [ T ] ∑ y k ∈ C r ( f 0 − f k ) d e g ( ℳ ( T , f 0 , … , f k , y 0 , … , y k ) ) ⋅ [ y k ] m_{k}([y_{0}],...,[y_{k-1}])=\sum_{[T]}\sum_{y_{k}\in Cr(f_{0}-f_{k})}deg({\cal M}(T;f_{0},...,f_{k};y_{0},...,y_{k}))\cdot[y_{k}]
where [ T ] [T] is the equivalence class of T T as an abstract oriented planar tree,
and d e g ( ⋅ ) ∈ 𝐙 deg(\cdot)\in{\bf Z} is the total number of points counted with signs, as
before.