of social benefits to social costs. (The social benefit part of the ratio is calculated by multiplying the proposed quantity of outputs from a workplace by their indicative prices, adding negative prices for any proposed pollution emissions and summing. The social costs are calculated by multiplying the quantity of requested inputs by their indicative prices and summing.) Proposals with a benefits-to-cost ratio below one will need to make adjustments in order to gain approval in the next round, either by switching to a less polluting technology, producing a more socially desirable set of outputs, or using less costly inputs. After receiving the revised proposals, the facilitation board once again updates the list of indicative prices. After several rounds of this revision and resubmission process, the result is convergence to a feasible plan in which workers and consumers are able to accomplish the activities that they detailed in their final submissions. Even after a feasible plan is achieved, flexible mid-year revisions of consumer/worker proposals can also be incorporated into the planning process. In academic work, Albert and Hahnel prove that participatory planning arrives at a Pareto optimum, and does so under less restrictive assumptions than markets; that is, participatory planning is Pareto optimal even though it incorporates both public goods and externalities, whereas markets do not achieve Pareto optimality with these two assumptions. A feature of participatory planning which differs from other modes of democratic planning is that all deliberation on proposals occurs within councils, but does not take place between councils. That is, under parecon, a feasible economic plan is constructed due to an iterative adjustment of prices based on the information from councils' self-activity proposals, rather than owing to a procedure of deliberation among delegates from various workplaces/industries. This is potentially desirable by cutting down on the meeting time and bureaucratic burdens needed to converge on an annual plan. Facilitation boards In a proposed participatory economy, key information relevant to converging on an economic plan would be made available by Iteration Facilitation Boards (IFBs), which, based on proposals from worker/consumer councils and economic data, present indicative prices and economic projections at each round of the planning process. The IFB has no decision-making authority. In theory, the IFB's activity can consist mainly of computers performing the (agreed upon) algorithms for adjusting prices and forecasts, with little human involvement. Motivations (opposition to central planning and capitalism) Robin Hahnel has argued that