Horse collar of the Oseberg ship burial). The problem with a breastcollar harness was that the actual shafts of the cart, chariot, or other vehicle are attached to a surcingle around the barrel of the horse. The breastplate primarily kept the surcingle from slipping back, not as the primary pushing object. This results in the horse literally pulling the load, a less efficient use of the animal. The modern breastcollar has traces which transfer the pull directly from the breastcollar, but a horse collar still is more effective for pulling heavy loads. After the breastcollar harness, the next and final evolutionary stage
Matroid girth oracle, it is impossible to find the girth using a subexponential number of matroid queries. Similarly, for a real linear matroid of rank , with elements, described by an oracle that gives the orientation of any -tuple of elements, it requires formula_1 oracle queries to determine the girth. Computations using a girth oracle (an oracle that reports the smallest dependent subset of a given set of elements) have also been considered. Matroid girth In matroid theory, a mathematical discipline, the girth of a matroid is the size of its smallest circuit or dependent set. The cogirth of a matroid is