In his opinion on the Microsoft antitrust case, Judge Jackson wrote: "[T] here main facts indicate that Microsoft enjoys monopoly power. First, Microsoft's share of the market for Intel-compatible PC operating systems is extremely large and stable. Second, Microsoft's dominant market share is protected by a high barrier to entry. Third, and largely as a result of that barrier,
Microsoft's customers lack a commercially viable alternative to Windows." (See the website reference, section 34, in this chapter's Further Readings.) Why are these elements related to monopoly? Are all three necessary? If not, which ones are crucial? Explain your reasoning.