diff --git a/prism/src/common/StopWatch.java b/prism/src/common/StopWatch.java
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+//==============================================================================
+//	
+//	Copyright (c) 2015-
+//	Authors:
+//	* Joachim Klein <klein@tcs.inf.tu-dresden.de> (TU Dresden)
+//	* Steffen Maercker <maercker@tcs.inf.tu-dresden.de> (TU Dresden)
+//	
+//------------------------------------------------------------------------------
+//	
+//	This file is part of PRISM.
+//	
+//	PRISM is free software; you can redistribute it and/or modify
+//	it under the terms of the GNU General Public License as published by
+//	the Free Software Foundation; either version 2 of the License, or
+//	(at your option) any later version.
+//	
+//	PRISM is distributed in the hope that it will be useful,
+//	but WITHOUT ANY WARRANTY; without even the implied warranty of
+//	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//	GNU General Public License for more details.
+//	
+//	You should have received a copy of the GNU General Public License
+//	along with PRISM; if not, write to the Free Software Foundation,
+//	Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+//	
+//==============================================================================
+
+package common;
+
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import prism.PrismLog;
+
+/**
+ * Stop watch for keeping track of the runtime of some computation,
+ * optionally printing the elapsed time to the log after the computation
+ * has stopped.
+ * <br>
+ * Example usage:
+ * <pre>
+ * StopWatch timer = new StopWatch(log);
+ * timer.start("model checking");
+ * // ... do the actual computation ...
+ * timer.stop();
+ * </pre>
+ * would result in the output
+ * <pre>
+ * Time for model checking 42.00 seconds.
+ * </pre>
+ * <br>
+ * Stopping via
+ * <pre>
+ * timer.stop("result was xyz");
+ * </pre>
+ * results in
+ * <pre>
+ * Time for model checking 42.00 seconds, result was xyz.
+ * </pre>
+ */
+public class StopWatch
+{
+	/** The (optional) log */
+	protected PrismLog log;
+
+	/** An (optional) task description */
+	protected String taskDescription;
+
+	/** For storing the time */
+	protected long time = 0;
+
+	/** Is watch running? */
+	protected boolean running = false;
+
+	/** Constructor, no log and no output */
+	public StopWatch()
+	{
+	}
+
+	/** Constructor, stores log for output */
+	public StopWatch(PrismLog log)
+	{
+		this.log = log;
+	}
+
+	/** Start the stop watch (without task description) */
+	public void start()
+	{
+		start(null);
+	}
+
+	/** Start the stop watch, store task description (may be {@code null}) */
+	public void start(String taskDescription)
+	{
+		this.taskDescription = taskDescription;
+		running = true;
+		time = System.currentTimeMillis();
+	}
+
+	/**
+	 * Stop the stop watch.
+	 * If a task description and a log was given, output elapsed time.
+	 * @return elapsed time in milliseconds
+	 */
+	public long stop()
+	{
+		return stop(null);
+	}
+
+	/**
+	 * Stop the stop watch, optionally taking extra text for output.
+	 * If a log and a task description / extra text was given, output
+	 * elapsed time.
+	 * <br>
+	 * Extra text is output as "... xx.yy seconds, extra-text."
+	 * @param extraText extra text to output (optional, ignored if {@code null})
+	 */
+	public long stop(String extraText)
+	{
+		time = System.currentTimeMillis() - time;
+		running = false;
+		if (log != null) {
+			if (taskDescription != null) {
+				log.print("Time for " + taskDescription + ": " + elapsedSeconds() + " seconds");
+				if (extraText != null) {
+					log.print(", " + extraText);
+				}
+				log.println(".");
+			} else if (extraText != null) {
+				log.println("Time: " + elapsedSeconds() + " seconds, " + extraText + ".");
+			}
+		}
+		return time;
+	}
+
+	/** Get the number of elapsed milliseconds (fixed value after having called stop). */
+	public long elapsedMillis()
+	{
+		return running ? System.currentTimeMillis() - time : time;
+	}
+
+	/** Get the number of elapsed seconds (fixed value after having called stop). */
+	public double elapsedSeconds()
+	{
+		return elapsedMillis() / 1000.0;
+	}
+
+	/**
+	 * Stop the execution time of a task.
+	 *
+	 * @return time in milliseconds
+	 **/
+	public long run(Runnable task)
+	{
+		return run(task, null, null);
+	}
+
+	/**
+	 * Stop the execution time of a task.
+	 *
+	 * @param taskDescription description or {@code null})
+	 * @param extraText text or {@code null}
+	 * @return time in milliseconds
+	 **/
+	public long run(Runnable task, String taskDescription, String extraText)
+	{
+		start(taskDescription);
+		task.run();
+		return stop(extraText);
+	}
+
+	/**
+	 * Stop the execution time of a task and return the result.
+	 * Time is available via {@code elapsedMillis()} and {@code elapsedSeconds()}.
+	 *
+	 * @return task result
+	 **/
+	public <T> T run(Supplier<T> task)
+	{
+		return run(task, null, (String) null);
+	}
+
+	/**
+	 * Stop the execution time of a task and return the result.
+	 * Time is available via {@code elapsedMillis()} and {@code elapsedSeconds()}.
+	 *
+	 * @param taskDescription description or {@code null}
+	 * @param extraText text or {@code null}
+	 * @return task result
+	 **/
+	public <T> T run(Supplier<T> task, String taskDescription, String extraText)
+	{
+		start(taskDescription);
+		T result = task.get();
+		stop(extraText);
+		return result;
+	}
+
+	/**
+	 * Stop the execution time of a task and return the result.
+	 * Time is available via {@code elapsedMillis()} and {@code elapsedSeconds()}.
+	 *
+	 * @param taskDescription description or {@code null}
+	 * @param resultDescription function that provides a description or {@code null}
+	 * @return task result
+	 **/
+	public <T> T run(Supplier<T> task, String taskDescription, Function<? super T, String> resultDescription)
+	{
+		start(taskDescription);
+		T result = task.get();
+		stop(resultDescription.apply(result));
+		return result;
+	}
+}