Mixed Heegaard Floer invariant

ID: mixed-heegaard-floer-invariant

For a closed smooth oriented four-manifold with , remove two balls to obtain , and choose an Admissible cut for a Heegaard Floer mixed map. Positivity and naturality show that the minus map of lands in , while the plus map of descends from . Thus
The coefficient of the bottom plus generator in this map, applied to , defines , up to the orientation sign, with . It vanishes unless . The construction is independent of the admissible cut by the cobordism composition and associativity laws. Two positive pieces explain the condition .

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