

Problems Nobody Has Solved Yet Here is a list of problems for which I have as yet seen no correct solutions, arranged by Difficulty Rating. DR1 problems DR3 problems PAC#33, CC#167, CC#168, CC#173, CC#211, CC#215, CC#232, CC#279, CC#285. DR4 problems #442, PAC#32, CC#144, CC#224, CC#228, CC#236, CC#276, CC#290. DR5 problems #397, #444, #514, EB#27, EB#44, Y#8, CC#139. DR6 problems #392, #399, #433, #464, #468, #499, #515, EB#45, Y#15, CC#146, CC#152, EB#45. DR7 problems DR8 problems 