By Shristi Achar A and Johann M Cherian Dec 12 (Reuters) - Wall Street's main indexes edged higher on Tuesday, following inflation data that kept expectations of a rate cut in May intact, while investors awaited the Federal Reserve's policy decision later in the week. November Consumer Price Index (CPI) rose 3.1% on an annual basis, in line with estimates from economists polled by Reuters. All eyes are now on the Fed's interest rate verdict at the end of its two-day meeting on Wednesday, as well as the producer price index (PPI) data for November.