MUDs

Introduction

Now, there are several thousand of them.

Hundreds of papers have been written on the subject..

But these are mainly from a Social Science perspective:

• Anthropology, Psychology, Sociology, Education, Gender Studies.

There's very little formal work in the core technologies

• because MUDs are "just a game".

Well no... MUDs are not "just a game".

MUDs:

• have useful applications
• are of great interest to people studying the human condition
• are a marvellous application domain for many AI techniques.

What is a MUD?

• a massively-multiplayer online game
• a (usually) text-based virtual reality
• a timesharing system with command line interface
• a real-time database with natural language interface
• a complete waste of time and money...

Perhaps an operational definition might be of more help:

•     you're told what's going on
•     you say what you want to do, if anything
•     you're told how whatever you wanted to do works out
•     you repeat the above until you, the MUD or Reality calls it off.

So a MUD is basically a shared virtual world operating in real time...

How do MUDs Work?

• user cranks up some client software, e.g.. telnet
• client software connects to server, establishes identity etc..
• client passes user input to server
• server parses input into some internal command format
• server applies command in current context
  • sometimes, server generates its own commands without user involvement
• server informs all relevant clients of the command's effects
• client displays any output it receives.

Server normally executes on a per command basis, but doesn't have to - some servers effect timesharing at a lower level.

Gratuitous Screenshot

The MUD Family Tree

• A lot of work, but much kudos!

Most of the MUDs in use today are "stock MUDs".

• Free MUD server software is available on the net.
• MUDs using the same code base tend to be similar.

The cutting edge of MUD technology comes in five places:

• new milieux and applications for MUDs
• increasing object functionality within a MUD
• implementing tightly bound clients and servers
• extending code bases
• writing new servers from scratch.

Practically all MUDs are direct descendants of Essex's MUD (MUD1).

Useful Applications

But MUDs also used for things like:

• Education
  • Teaching children how to program.
  • EFL.
• Training
  • Business role-playing scenarios.
• Conferencing
  • Informal workshops.
• Therapy
  • Social engineering.
  • Rape counselling.

Topic of Study

• they are microcosms of reality
• they can be used experimentally
• great swathes of empirical data can be collected automatically.

On an individual level, MUDs are interest because:

• they promote personal development
  • two approaches, British and American
• they are (usually) meritocracies
• they grant the freedom of anonymity
• they are places you can visit.

On a technical level, MUDs tend to be studied only from a networking or client/server perspective.

Application Domain

• Main work in this area has been on "bots".

MUDs force you to address some real issues:

• this is a shared world
• there are real human beings in it
• it's all done in real time

But MUDs do draw the line, at places convenient for AI:

• MUD worlds are discrete, not continuous
• all users (human and AI) use the same interface
• the structure of a command is explicitly available

MUDs are good places to integrate areas of AI.

• More on this later...

Current State of the Art

Commercial systems concentrating on "graphical MUDs".

• Normal people expect "professional quality".
• Need pictures to get the games magazines to run features.
• Raises the ante beyond the reach of developers of free MUDs.

Some important MUD development work going on at research centres, though.

• Mainly in the USA.
• MIT in particular.

MUDs are starting to appear in course modules.

• Mainly in the USA
• Almost always from without, not from within.

MUDs and AI (#1)

• MUD commands as planning operators.
• MUD engine as plan execution module.

Good for speech acts.

• Communication is at the very core of MUDs.
• You really can't do some things without co-operation.
• But some people may be out to get you...

Goodish for plan recognition.

• Limited range of overall goals.
• Lots of ways of achieving those goals.
• Difficult to determine which actions go together.
• People often abandon goals.

MUDs and AI (#2)

• parsing input commands
• parsing what other users say to you.

Parsing input commands isn't a problem.

• Only imperative commands - syntax is limited.
• Just need to be flexible and report errors informatively.
• Users soon learn the right format...

Parsing what other users say is a major problem.

• Grammar and spelling are alien concepts.
• They talk about several things at once.
• They go off-topic.
• But you can get a long way using pattern-matching.

MUDs and AI (#3)

• not too hard if you don't mind stock phrases and repetition
• not responding is a form of response.

The other major area of interest is learning.

• Extracting information about the virtual world.
• Updating information about the virtual world.
• Hypothesising about the current state of the virtual world.
• Profiles of the other users.

Integrating all this together is exciting.

• Common data structures for multiple uses.
• Belief versus knowledge.
• But complete operational model required, from input to output..

MUDs and Programming

• Most use a C++ kind of syntax and semantics.
• Objects can be created, tested and modified on the fly.
• Lots of functionality to play with.

Some disadvantages to this...

• Single inheritance rules.
• Artificial constraints to stop hangs and crashes.
• Aesthetically, most of what people produce is utter rubbish.
• Virtual world objects are programming objects.

MUDDLE! Like Prolog but:

• with variables typed in a multiple inheritance hierarchy
• implicitness of cut/search is reversed.

MUDDLE Example

Conclusion

• Prof. Ray Turner, 1988.

Well, not to everyone.