$1.$ Lilly worked for Sam Software for twelve years and then resigned to start her own firm, Lilly Likeware. Sam Software and Lilly Likeware compete directly for the same customers. According to recent data, Sam Software's market share has dropped from $50$ percent to $30$ percent. During the same time, Lilly Likeware's market share has risen from $0$ to $20$ percent. Within the past weeks, however, Lilly believes Sam Software is participating in below$-$cost pricing. What is below$-$cost pricing? How can it be shown? What antitrust law or laws might apply to this situation?