I have a datasets with information like age, city, age of children, ... and a result (confirm, accept).
To help modelisation of "workflow", I want to create automatically a decision tree based on previous datasets.
I have take a look at http://en.wikipedia.org/wiki/Decision_tree_learning and I know that the problem is clearly not obvious.
I just want to have advice on some algorithm or some libs on this subject what can help me in the contruction of a decision tree based on samples.
You should take a look at Weka, a free Java-based supervised learning suite.
After converting your data into Weka's simple text-based .arff format, you should be able to use the GUI or command-line interface to train and test a variety of different classifiers on that data, including:
Experimenting with this interface should allow you to easily try different classifiers and training parameters to determine which ones perform the best on your data.
You can also use an API to integrate Weka into your own source code.