Stephen L Hansen, Ph.D.

Biography:

My Ph.D. is from Nova Southeastern University, in 2000.  I have been involved in industrial development of data communication software and systems for nearly 20 years, presently with Xpedite, Inc.    I do some adjunct teaching for Nova Southeastern University.  My most recent industrial project is MessageReach.com .   My resume is here .  

Contact Information:

Students should normally contact me via email to: hansens@nova.edu .  Be sure to include the name of the course (e.g. MMIS 640) in the subject.  I use filters to select course-name subjects into separate folders.  Because of the volume of junk mail, it is very easy for me to overlook items that do not have indicative subjects.

Snail Mail:   
c/o Xpedite Systems, Inc.
824 South  Military Trail
Deerfield Beach, FL  33442

Email: 

hansensl@acm.org     (permanent)
hansens@nova.edu     (scis-related stuff)
Telephone:
1-954-581-2856   (leave message)
1-954-547-0498   (cell phone, urgent calls only

Research Interests:

My research interests are primarily in high-confidence software development, software correctness, and discrete optimization.  This leads to a wide variety of particular topics, which include many NP roblems.  NP problems can be found in every area of computer science. Many of the unsolved problems in computer science are NP problems, or are closely related.  Conventional wisdom seems to be that one should not attempt to actually solve NP problems. Instead, the usual approaches are to either find a relaxation of the problem that can be solved, or to find an acceptable approximation to the solution of the hard problem.   For many applications a suboptimal solution is acceptable.

For the purpose of developing software for applications where the cost of failure is unacceptable, it is essential that the sofware is actually correct.  Applications such as vehicle control, medical apparatus, emergency services, and communications require that the software must be of the highest quality, and ideally that safety properties of the software must be proved.   The problem of developing correct sofware, and proving correctness properties of that software, is a fundamental problem in computer science.  Even the simplest cases are NP hard.

My dissertation research was to develop algorithms that might be useful to solve one type of NP complete problem, and which might eventually lead to algorithms that can be used prove software properties.  My advisor was Lee Leitner, Ph.D.

Online Libraries:

The following online libraries provide access to much of the recent computer science literature: I have also found the following bibliographic search resources to be very useful:
If you find another wonderful bibliographic resource, please send me the url .
 

ACM Membership:

Membership in the Association for Computing Machinery is very worthwhile and very affordable.  The ACM offers students very inexpensive student memberships , which includes very low dues and discounts on journals.  The Student Power Package includes two journals and unlimited access to the online Digital Library for only $38.   The digital library alone is well worth several times the price.  The ability to access a large fraction of the journal and conference literature online, without waiting for the library to retrieve the papers, gives a student a significant advantage.  The student membership application form is also linked from the bottom of the student membership information page.


Last Modified: April 02, 2002