Failing the four-gamete test enables exact phasing: the Corners' Algorithm.
Luis Gomez-RayaWendy M RauwPublished in: Genetics, selection, evolution : GSE (2022)
The Corner's Algorithm allows to fully phase haplotypes when the four-gamete test fails. Longer haplotypes in chromosomal regions in which the four-gamete test fails for any pair of SNPs can be used as a multi-allelic marker with increased polymorphism information content.