Fast Artificial Neural Network (FANN) library is a free open source neural network library, which implements multilayer artificial neural networks in C with support for both fully connected and sparsely connected networks. FANN webpage: http://leenissen.dk/fann/
CL-FANN provides common lisp bindings to FANN by using CFFI (http://common-lisp.net/project/cffi/).
These details are provided for information only. No information here is legal advice and should not be used as such.