CrossCat is a generative model that can be used for categorizing objects given their features. The model assumes that each data point is generated using multiple systems of categories; each such system accounts for some subset of the features.

```
(define samples
(mh-query 300 100
(define kind-distribution (DPmem 1.0 gensym))
(define feature->kind
(mem (lambda (feature) (kind-distribution))))
(define kind->class-distribution
(mem (lambda (kind) (DPmem 1.0 gensym))))
(define feature-kind/object->class
(mem (lambda (kind object) ((kind->class-distribution kind)))))
(define class->parameters
(mem (lambda (object-class) (beta 1 1))))
(define (observe object feature)
(flip (class->parameters
(feature-kind/object->class (feature->kind feature)
object))))
(list (observe 'spinach 'breakfast)
(observe 'eggs 'breakfast))
(and (observe 'eggs 'breakfast)
(observe 'toast 'breakfast)
(observe 'eggs 'dinner)
(observe 'spinach 'dinner))))
(hist samples)
```

References:

- Cite:Shafto2006tz
- Cite:ProbMods
- CrossCat at MIT