Construction
Tract associated with a partial hyperfield
The tract obtained from the ambient null hypersums of a partial hyperfield.
Core idea
Let be a partial hyperfield, with a subgroup of the units of the ambient integral hyperring . Its associated tract has multiplicative group and null set
The construction uses the ambient hypersum in , not only binary partial sums that remain visible in . It therefore records null relations even when every attempted parenthesization passes through elements outside the selected coefficient set.
For an ordinary ambient ring this specializes to the partial-field construction. Taking with a hyperfield specializes to the hyperfield construction.
References
Matthew Baker and Nathan Bowler, “Matroids over partial hyperstructures,” Advances in Mathematics 343 (2019), 821–863. arXiv:1709.09707.