[page 95] ... fundamental concepts of market power and competition are but the inverse of each other. ...

[page 96] ... effective competition proceeds through the availability of substitutes, both in demand and supply, which act as constraints on each individual firm's market power.

[page 96] Competition is a process rather than a situation. Dynamic processes of substitution are at work. Technological change in products and processes, whether small or large, is ongoing and there are changing tastes and shifting demographic and locational factors to which business firms respond. ... effective competition is fully compatible with the existence of strictly "limited monopolies" resting upon some short run advantage or upon distinctive characteristics of product (including location). Where there is effective competition, it is the on-going substitution process that ensures that any achievement of market power will be transitory.

[page 126] It must be constantly borne in mind that market definition is but a tool to facilitate a proper orientation for the analysis of market power and competitive processes - and should be taken only a sufficient distance to achieve the legal decision. There may be more than one relevant market for a particular case in the sense of markets that would attract liability. [cited in the Arnotts case para 48]

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