The Bombay Stock Exchange benchmark Sensex today opened 57 points higher. Funds made cautious buying as the Reserve Bank of India will announce it quarterly credit policy later in the day.The 30-share BSE barometer rose to 18,077 points. The index had lost 111 points on Monday.The wide-based National Stock Exchange's Nifty also moved up by 15.15 points to 5,433.75 points.