1. Title: Mushroom Database (modified for instructional purposes)

2. Sources: 
    (a) Mushroom records drawn from The Audubon Society Field Guide to North
        American Mushrooms (1981). G. H. Lincoff (Pres.), New York: Alfred
        A. Knopf
    (b) Donor: Jeff Schlimmer
    (c) Date: 27 April 1987


3. Logical rules for the mushroom data sets.
  
    Logical rules given below seem to be the simplest possible for the
    mushroom dataset and therefore should be treated as benchmark results.
  
    Disjunctive rules for poisonous mushrooms, from most general
    to most specific:
  
    P_1) odor=NOT(almond.OR.anise.OR.none)
         120 poisonous cases missed, 98.52% accuracy
  
    P_2) spore-print-color=green
         48 cases missed, 99.41% accuracy
           
    P_3) odor=none.AND.stalk-surface-below-ring=scaly.AND.
              (stalk-color-above-ring=NOT.brown) 
         8 cases missed, 99.90% accuracy
           
    P_4) habitat=leaves.AND.cap-color=white
             100% accuracy     
  
    Rule P_4) may also be
  
    P_4') population=clustered.AND.cap_color=white
  
    These rule involve 6 attributes (out of 22). Rules for edible
    mushrooms are obtained as negation of the rules given above, for
    example the rule:
  
    odor=(almond.OR.anise.OR.none).AND.spore-print-color=NOT.green
  
    gives 48 errors, or 99.41% accuracy on the whole dataset.
  
    Several slightly more complex variations on these rules exist,
    involving other attributes, such as gill_size, gill_spacing,
    stalk_surface_above_ring, but the rules given above are the simplest
    we have found.
  

4. Relevant Information:
    This data set includes descriptions of hypothetical samples
    corresponding to 23 species of gilled mushrooms in the Agaricus and
    Lepiota Family (pp. 500-525).  Each species is identified as
    definitely edible, definitely poisonous, or of unknown edibility and
    not recommended.  This latter class was combined with the poisonous
    one.  The Guide clearly states that there is no simple rule for
    determining the edibility of a mushroom; no rule like ``leaflets
    three, let it be'' for Poisonous Oak and Ivy.

5. Number of Instances: 5644

6. Number of Attributes: 22 (all nominally valued)

7. Attribute Information: (classes: edible=e, poisonous=p)
     1. cap-shape:                bell=b,conical=c,convex=x,flat=f,
                                  knobbed=k,sunken=s
     2. cap-surface:              fibrous=f,grooves=g,scaly=y,smooth=s
     3. cap-color:                brown=n,buff=b,cinnamon=c,gray=g,green=r,
                                  pink=p,purple=u,red=e,white=w,yellow=y
     4. bruises?:                 bruises=t,no=f
     5. odor:                     almond=a,anise=l,creosote=c,fishy=y,foul=f,
                                  musty=m,none=n,pungent=p,spicy=s
     6. gill-attachment:          attached=a,descending=d,free=f,notched=n
     7. gill-spacing:             close=c,crowded=w,distant=d
     8. gill-size:                broad=b,narrow=n
     9. gill-color:               black=k,brown=n,buff=b,chocolate=h,gray=g,
                                  green=r,orange=o,pink=p,purple=u,red=e,
                                  white=w,yellow=y
    10. stalk-shape:              enlarging=e,tapering=t
    11. stalk-root:               bulbous=b,club=c,cup=u,equal=e,
                                  rhizomorphs=z,rooted=r
    12. stalk-surface-above-ring: ibrous=f,scaly=y,silky=k,smooth=s
    13. stalk-surface-below-ring: ibrous=f,scaly=y,silky=k,smooth=s
    14. stalk-color-above-ring:   brown=n,buff=b,cinnamon=c,gray=g,orange=o,
                                  pink=p,red=e,white=w,yellow=y
    15. stalk-color-below-ring:   brown=n,buff=b,cinnamon=c,gray=g,orange=o,
                                  pink=p,red=e,white=w,yellow=y
    16. veil-type:                partial=p,universal=u
    17. veil-color:               brown=n,orange=o,white=w,yellow=y
    18. ring-number:              none=n,one=o,two=t
    19. ring-type:                cobwebby=c,evanescent=e,flaring=f,large=l,
                                  none=n,pendant=p,sheathing=s,zone=z
    20. spore-print-color:        black=k,brown=n,buff=b,chocolate=h,green=r,
                                  orange=o,purple=u,white=w,yellow=y
    21. population:               abundant=a,clustered=c,numerous=n,
                                  scattered=s,several=v,solitary=y
    22. habitat:                  grasses=g,leaves=l,meadows=m,paths=p,
                                  urban=u,waste=w,woods=d

8. Class Distribution: 
    --    edible: 3488 (61.8%)
    -- poisonous: 2156 (38.2%)
    --     total: 5644 instances

9. Data File Format:
    One example per line with the class label and the 22 attributes
    separated by the space character.