By default, Surf computes the analytical models sequentially to share their
resources and update their actions. It is possible to run them in parallel,
using the \b surf/nthreads item (default value: 1). If you use a
-negative value, the amount of available cores is automatically
+negative or null value, the amount of available cores is automatically
detected and used instead.
Depending on the workload of the models and their complexity, you may get a
request to execute the user code in parallel. Several threads are
launched, each of them handling as much user contexts at each run. To
actiave this, set the \b contexts/nthreads item to the amount of
-cores that you have in your computer (or -1 to have the amount of cores
-auto-detected).
+cores that you have in your computer (or lower than 1 to have
+the amount of cores auto-detected).
Even if you asked several worker threads using the previous option,
you can request to start the parallel execution (and pay the
