Merge pull request #6 from tommens/patch-2

Update index.rst

docs/index.rst

@@ -20,24 +20,26 @@ Sismic Interactive State Machine Interpreter and Checker
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 Statecharts are a well-known visual language for modeling the executable behavior of complex reactive event-based systems.
-The Sismic library for Python >= 3.4 provides a set of tools to define, simulate, execute and debug statecharts.
+The Sismic library for Python >= 3.4 provides a set of tools to define, validate, simulate, execute and debug statecharts.
 More specifically, Sismic provides:
 
  - An easy way to define and to import statecharts, based on the human-friendly YAML markup language
- - A statechart interpreter offering discrete, step-by-step, and fully observable simulation engine
+ - A statechart interpreter offering a discrete, step-by-step, and fully observable simulation engine
  - Synchronous and asynchronous simulation, in real time or simulated time
  - Built-in support for expressing actions and guards using regular Python code
- - A design-by-contract programming approach for statecharts
- - A unit testing framework for statecharts that includes scenarios generators
+ - A design-by-contract approach for statecharts
+ - A unit testing framework for statecharts, including generation of test scenarios
 
-Sismic provides full support for the majority of the concepts of UML statecharts:
+Sismic provides full support for the majority of the UML 2 statechart concepts:
 
  - simple states, composite states, orthogonal (parallel) states, initial and final states, shallow and deep history states
  - state transitions, guarded transitions, automatic (eventless) transitions, internal transitions
  - statechart variables and their initialisation
  - state entry and exit actions, transition actions
  - internal and external events, parametrized events, timed events
 
+In addition to this, contracts can be specified to express invariants, pre- and postconditions on states, transitions and the statechart itself.
+
 The Sismic library is written in a modular way:
 
  - The semantics of the statechart interpreter is based on the specification of the SCXML semantics (with a few exceptions),