Santa Ana-based CoreLogic, a provider of real estate and mortgage databases and information, said Monday afternoon that it has hired investment banking firm Greenhill & Co., to explore "alternatives to enhance shareholder value." The firm said it is looking at everything from changes in capital structure, disposition of business lines, potential sale, or a business combination as a part of the effort. The firm cited "challenging" economic environment and current market conditions for the move. Typically, companies hire an investment bank to shop itself to buyers.