There are a number of software packages available for realization, most of which have been developed by academic research groups in NLG.
For example, the following Java code causes the simplenlg system [2] [1] to print out the text The women do not smoke.
: In this example, the computer program has specified the linguistic constituents of the sentence (verb, subject), and also linguistic features (plural subject, negated), and from this information the realiser has constructed the actual sentence.
These systems differ in terms of complexity and sophistication of their processing, robustness in dealing with unusual cases, and whether they are accessed programmatically via an API or whether they take a textual representation of a syntactic structure as their input.
There are also major differences in pragmatic factors such as documentation, support, licensing terms, speed and memory usage, etc.