Recurrent Neural Networks for Missing orAsynchronous

In this paper we propose recurrent neural networks with feedback into the input units for handling two types of data analysis problems. On the one hand, this scheme can be used for static data when some of the input variables are missing. On the other hand, it can also be used for sequential data, when some of the input variables are missing or are available at diierent frequencies. Unlike in the case of probabilistic models (e.g. Gaussian) of the missing variables, the network does not attempt to model the distribution of the missing variables given the observed variables. Instead it is a more \discriminant" approach that lls in the missing variables for the sole purpose of minimizing a learning criterion (e.g., to minimize an output error).