Merged in feature/update-readme (pull request #30) by ReBaZer

Update readme

README.md

@@ -1,9 +1,13 @@
 # GUI State Machine API
 
+[![Build Status](https://travis-ci.com/retest/gui-state-machine-api.svg?branch=master)](https://travis-ci.com/retest/gui-state-machine-api)
+[![Code Coverage](https://img.shields.io/codecov/c/github/retest/gui-state-machine-api/master.svg)](https://codecov.io/github/retest/gui-state-machine-api?branch=master)
+
 API for the creation and modification of incomplete state machines which represent the exploration of a GUI application.
 The states represent the GUI elements and the transitions represent the GUI actions.
 
 This is a small code example of creating a new state machine, adding two states connected with a transition and saving the state machine:
+
 ```scala
 import de.retest.guistatemachine.api.GuiStateMachineApi
 import de.retest.guistatemachine.api.GuiStateMachineSerializer
@@ -23,11 +27,6 @@ GuiStateMachineSerializer.gml(stateMachine).save("mystatemachine.gml")
 State machines can be saved as and loaded from files using Java object serialization/deserialization.
 Besides, they can be saved as [GML](https://en.wikipedia.org/wiki/Graph_Modelling_Language) files which can be visualized by editors like [yEd](https://www.yworks.com/products/yed).
 
-## Automatic Build with TravisCI
-
-[![Build Status](https://travis-ci.com/retest/gui-state-machine-api.svg?branch=master)](https://travis-ci.com/retest/gui-state-machine-api)
-[![Code Coverage](https://img.shields.io/codecov/c/github/retest/gui-state-machine-api/master.svg)](https://codecov.io/github/retest/gui-state-machine-api?branch=master)
-
 ## Build Credentials
 
 Define the Nexus password in the environment variable `TRAVIS_NEXUS_PW`.
@@ -47,19 +46,19 @@ Otherwise, the build will fail!
 * `sbt 'release cross with-defaults'` to create a release with a new version number which is added as tag. This command does also publish the artifacts.
 * `sbt publish` publishes the artifacts in ReTest's Nexus. Requires a `$HOME/.sbt/.credentials` file with the correct credentials. This command can be useful to publish SNAPSHOT versions.
 
-## NFA for the Representation of Tests
+## NFA for the Representation of GUI Behavior
 
-A nondeterministic finite automaton represents the states of the GUI during the test.
-The actions executed by the user on the widgets are represented by transitions.
-If an action has not been executed yet from a state, it leads to an unknown state.
+A nondeterministic finite automaton (NFA) represents the states of the GUI during testing.
+The actions executed by the user on GUI elements are represented by transitions.
+If an action has not been executed yet from a state, it leads to the so-called unknown state *s<sub>?</sub>*.
 The unknown state is a special state from which all actions could be executed.
-The NFA is based on the UI model from [Search-Based System Testing: High Coverage, No False Alarms](http://www.specmate.org/papers/2012-07-Search-basedSystemTesting-HighCoverageNoFalseAlarms.pdf) (section "4.5 UI Model").
-Whenever an unknown state is replaced by a newly discovered state, the NFA has to be updated.
+Whenever an action, which previously led to *s<sub>?</sub>*, is being executed and then leads to a newly discovered state, the NFA has to be updated.
+
+The NFA is based on the UI model from ["Search-Based System Testing: High Coverage, No False Alarms"](http://www.specmate.org/papers/2012-07-Search-basedSystemTesting-HighCoverageNoFalseAlarms.pdf) (section "4.5 UI Model"). Originally, it has been used together with a genetic algorithm for search-based system testing, where it served two purposes:
 
-The NFA is used to generate test cases (sequence of UI actions) with the help of a genetic algorithm.
-For example, whenever a random action is executed with the help of monkey testing, it adds a transition to the state machine.
-After running the genetic algorithm, the state machine is then used to create a test suite.
+1. Population initialization: to give precedence to unexplored actions.
+2. Mutation: to repair test cases.
 
 ## Concurrency
 
-The creation and modification of state machines should be threadsafe.
+The creation and modification of state machines should be thread-safe.