QCA can be performed probabilistically or deterministically with observations of categorical variables. Another interactive proof system characterizing NEXPTIME is a certain class of probabilistically checkable proofs. The algorithm formula 23 is called consistent if formula 33 probabilistically converges to formula 34. See probabilistically checkable proofs for more details. Similarly the dynamical system describing the evolution of the state variables is also known probabilistically. In a probabilistically checkable proof system, a proof is represented as a sequence of bits. So, they say, it only appears that things proceed in a merely probabilistically determinative way. This symmetry is represented probabilistically by exchangeability. However structure prediction by PCFGs is scored probabilistically rather than by minimum free energy calculation. This leads to the "predict" and "update" steps of the Kalman filter written probabilistically. By dropping packets probabilistically, AQM disciplines typically avoid both of these issues. If these conditions do not hold, then CoDel drops packets probabilistically. Several sample-based methods are probabilistically complete. He formulated the principle as a dominance principle, but it can also be framed probabilistically. The performance of a probabilistically complete planner is measured by the rate of convergence.