CEVAP:

A corner solution exists in a situation in which the budget line reaches the highest achievable indifference curve along an axis (the vertical axis). For example, the consumer may choose to spend all his or her income just on one good, good X. Of course, it is possible to spend all his or her income just on good Y. In this situation, the corner solution will be on the highest achievable indifference curve along the horizontal axis. In non technical terms, a corner solution is possible when the chooser is either unwilling or unable to make a tradeoff. It holds if there is a higher vs. lower preference between, and a perfect substition for two goods.