Assume that a material with a uniaxial yield stress Y yields under a stress state of principal stresses σ1, σ2, σ3, where σ1 > σ2 > σ3, Show that the superposition of a hydrostatic stress, p, on this system (such as placing the specimen in a chamber pressurized with a liquid) does not affect yielding. In other words, the material will still yield according to yield criteria.