Half-tetrads, where two meiotic products from a single meiosis are rec
overed together, arise in different forms in a variety of organisms. C
losely related to ordered tetrads, half-tetrads yield information on c
hromatid interference, chiasma interference, and centromere positions.
In this article, for different half-tetrad types and different marker
configurations, we derive the relations between multilocus half-tetra
d probabilities and multilocus ordered tetrad probabilities. These rel
ations are used to obtain equality and inequality constraints among mu
ltilocus half-tetrad probabilities that are imposed by the assumption
of no chromatid interference. We illustrate how to apply these results
to study chiasma interference and to map centromeres using multilocus
half-tetrad data.