摘要
This paper exhibits, for the first time in the literature, a continuous strictly increasing singular function with a derivative that takes non-zero finite values at some points. For all the known 鈥渃lassic鈥?singular functions鈥擟antor鈥檚, Hellinger鈥檚, Minkowski鈥檚, and the Riesz-N谩gy one, including its generalizations and variants鈥攖he derivative, when it existed and was finite, had to be zero. As a result, there arose a strong suspicion (almost a conjecture) that this had to be the case for any singular function. We present here a singular function, constructed as a patchwork of known classic singular functions, with derivative 1 on a subset of the Cantor set.