Gruppe 3: MYCIN

Introduction

MYCIN in an expert system that helps the doctor to identify bacteria causing severe infections, such as bacteremia and meningitis. It is a system from the 1970s and runs as a command-line application; in other words, there is no Graphical User Interface (GUI), icons, or images, and the mouse cannot be used.

To use MYCIN we will access it via a browser.

Visit https://jupyterhub.duckdns.org using Firefox or Internet Explorer.

You will the see the following login screen:

Ask the professor for log in details.

You will see the following:

Click New → Terminal (shown below)

You will then see the following:

Type mycin.sh and press Enter/Return to start the MYCIN programme. You will see something similar to the following:

The MYCIN programme has started.

Using MYCIN

At any time you can type HELP to see what commands you can use. Let's type HELP to start with.

1. Type HELP to see the available commands: 

------- patient-1 -------

Patient's name:  HELP
 Type one of the following:
    ?       - to see possible answers for this parameter
    rule    - to show current rule
    why     - to see why this question is asked
    help    - to see this list
    xxx     - (for some specific xxx) if there
              is a definite answer
    xxx .5 yyy .4 - if there are several answers with
                different certainty factors

As you can see there are a number of commands you can use.

2. Now we will enter the patient's name. Use any name you want: 

Patient's name:  GUY_INCOGNITO

3. Enter MALE as the patient's sex: 

Sex:  MALE

4. Enter 32 as the patient's age: 

Age:  32

Once the patient's details are known, MYCIN will now ask you some questions about the culture. Do not forget, you can type ? at any time to see a list of possible answers.

5. Answer BLOOD. 

------- culture-1 -------

From what site was specimen CULTURE-1 taken?  BLOOD

6. Type 3 to specify when the culture was obtained: 

How many days ago was this
  culture (CULTURE-1) obtained?  3

Now you are asked a series of questions regarding the organism.

7. For its identity, type UNKNOWN. 

------- organism-1 -------

Enter the identity (genus) of ORGANISM-1?  UNKNOWN

Don't forget that you can always type ? for a list of possible answers.

8. First type ? to see a list of possible answers, then answer NEG. 

The gram strain of ORGANISM-1?  ?
Must be one of: acid-fast, pos, neg

The gram strain of ORGANISM-1?  NEG

Specify if the organism's morphology is rod or coccus.

9. Type ROD. 

Is ORGANISM-1 a rod or coccus?  ROD

MYCIN will now ask if the patient is a burn patient. If MYCIN makes a suggestion you can ask why it came to this conclusion.

10. Type WHY and hit return to see MYCIN's reasoning: 

Is PATIENT-1 a burn patient? If so, mild or serious? WHY
[Why is the value of burn being asked for?]
It is known that:
    The site of the culture is blood
    The gram of the organism is neg
    The morphology of the organism is rod
Therefore,
Rule 52:
    If  The burn of the patient is serious
    Then with certainty of 0.4
      The identity of the organism is pseudomonas

You can see MYCIN's rule-based inference engine at work.

11. Type SERIOUS for MYCIN's question about the burn status and hit return: 

Is PATIENT-1 a burn patient?
  If so, mild or serious? SERIOUS

MYCIN will now ask for the aerobicity of the organism.

12. Type AEROBIC

What is the aerobicity of ORGANISM-1? AEROBIC

MYCIN will now ask if the patient is a comprised host (a comprised host is a patient who is less than normally able to resist infection because of immunosuppressive therapy, immunologic defect, severe anemia, or concurrent disease or condition, including HIV or malnutrition—Mosby's Medical Dictionary, 8th edition).

13. Answer YES 

Is PATIENT-1 a compromised host? YES
Findings for ORGANISM-1
    for these goals: identity
    IDENTITY: ENTERO 0.8, PSEUDOMONAS 0.76

MYCIN has decided with a probability of 0.8 that the identity is entero, and with a probability of 0.76 that the identity is pseudomonas.

14. Answer NO to the final questions to end the session: 

Is there another organism? NO
Is there another culture? NO
Is there another patient? NO

MYCIN ends.

To restart MYCIN just type mycin.sh and press Enter/Return again.

Beurteilung

  1. Download the questions: g3-antwortbogen-en.docx
  2. Answer the questions as best you can.
  3. Send your answers by email.

Important Notes

Important things to remember:

References/Resources

See http://en.wikibooks.org/wiki/Expert_Systems/MYCIN for background information.

Technical information regarding the inference engine can be found here: http://www.cs.utexas.edu/users/novak/tmycin.html.

Also see http://www.cs.cf.ac.uk/Dave/AI1/mycin.html for a discussion.

MYCIN source code courtesy of http://lazax.com/software/Mycin/mycin.html.

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