[D] Had fun with OpenAi's lstm parity prediction problem. Any other deceptively hard ML toy problems? • r/MachineLearning

It asks to use an LSTM and predict the parity of bit sequences of length 50. Naive attempts didn't work (large hidden state, different rnn cells, different optimization algos, etc). It was a fun challenge. I like that it's very easy to state but requires a bit of insight to figure out. Do you know of any others like that?