;;;; -*- Mode: Lisp; Syntax: Common-Lisp -*-
;;;; Code from Paradigms of AI Programming
;;;; Copyright (c) 1991 Peter Norvig

> (mycin)
------ PATIENT-1 ------
Patient's name: Sylvia Fischer
Sex: female
Age: 27
------ CULTURE-1 ------
From what site was the specimen for CULTURE-1 taken? blood
How many days ago was this culture (CULTURE-1) obtained? 3
------ ORGANISM-1 ------
Enter the identity (genus) of ORGANISM-1: unknown
The gram stain of ORGANISM-1: ?
A GRAM must be of type (MEMBER ACID-FAST POS NEG)
The gram stain of ORGANISM-1: neg

Is ORGANISM-1 a rod or coccus (etc.): rod
What is the AEROBICITY of ORGANISM-1? why
[Why is the value of AEROBICITY being asked for?]
It is known that:
    1) THE GRAM OF THE ORGANISM IS NEG
    2) THE MORPHOLOGY OF THE ORGANISM IS ROD
Therefore,
Rule 107:
  If
    1) THE AEROBICITY OF THE ORGANISM IS AEROBIC
  Then there is suggestive evidence (0.8) that
    1) THE IDENTITY OF THE ORGANISM IS ENTEROBACTERIACEAE 

What is the AEROBICITY of ORGANISM-1? aerobic
Is Sylvia Fischer a compromised host? yes
Is Sylvia Fischer a burn patient?  If so, mild or serious? why
[Why is the value of BURN being asked for?]
It is known that:
    1) THE SITE OF THE CULTURE IS BLOOD
    2) THE GRAM OF THE ORGANISM IS NEG
    3) THE MORPHOLOGY OF THE ORGANISM IS ROD
Therefore,
Rule 52:
  If
    1) THE BURN OF THE PATIENT IS SERIOUS
  Then there is weakly suggestive evidence (0.4) that
    1) THE IDENTITY OF THE ORGANISM IS PSEUDOMONAS 
Is Sylvia Fischer a burn patient?  If so, mild or serious? serious
Findings for ORGANISM-1:
 IDENTITY: ENTEROBACTERIACEAE (0.800)   PSEUDOMONAS (0.760)  

Is there another ORGANISM? (Y or N) Y
------ ORGANISM-2 ------
Enter the identity (genus) of ORGANISM-2: unknown
The gram stain of ORGANISM-2: (neg .8 pos .2)
Is ORGANISM-2 a rod or coccus (etc.): rod
What is the AEROBICITY of ORGANISM-2?  anaerobic

Findings for ORGANISM-2:
 IDENTITY: BACTEROIDES (0.720)   PSEUDOMONAS (0.646)  

Is there another ORGANISM? (Y or N) N
Is there another CULTURE? (Y or N) N
Is there another PATIENT? (Y or N) N

;;;; If you add the following rules, then rerun the last case above,
;;;; MYCIN will do backward chaining.  See section 16.8.

(defparm wbc patient number
  "What is ~a's white blood cell count?")

(defrule 1
  if (immunosuppressed patient is yes)
  then 1.0 (compromised-host patient is yes))

(defrule 2
  if (leukopenia patient is yes)
  then 1.0 (immunosuppressed patient is yes))

(defrule 3
  if (wbc patient < 2.5)
  then .9 (leukopenia patient is yes))