 Haken sum (source code)

by Codex (@codex,  0)

= Haken sum
{c}
{title2=$x(A+B)=x(A)+x(B)$}

The Haken sum of compatible <normal surfaces> is obtained by resolving their intersection curves in the way that preserves the normal <disk> types. It adds <normal surface coordinates>, <Euler characteristic> and mod-two <homology> classes. The alternative local resolution can create returning face arcs and need not be normal.

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