anchor.diff:      (setf (slot-value cloud 'weights)
             (matlisp:make-real-matrix (chunk-size (chunk2 cloud))
                                       (chunk-size (chunk1 cloud))))
  -    (map-into (storage (weights cloud))
  -              (lambda () (flt (* 0.01 (gaussian-random-1)))))))
  +    (unless (or (conditioning-chunk-p (chunk1 cloud))
  +                (conditioning-chunk-p (chunk2 cloud)))
  +      (map-into (storage (weights cloud))
  +                (lambda () (flt (* 0.01 (gaussian-random-1))))))))
   
   (defmacro do-cloud-runs (((start end) cloud) &body body)
     "Iterate over consecutive runs of weights present in CLOUD."
  
positive.code:       (setf (slot-value chunk 'nodes)
              (matlisp:make-real-matrix size max-n-stripes))
        (setf (slot-value chunk 'old-nodes)
              (if (conditioning-chunk-p chunk)
                  (nodes chunk)
                  (matlisp:make-real-matrix size max-n-stripes)))
        (fill-chunk chunk (default-value chunk) :allp t)
        (setf (slot-value chunk 'inputs)
              (if (typep chunk 'conditioning-chunk)
  
negative.code: into a product of two matrices: A*B. At activation time, HIDDEN +=
  A*B*VISIBLE."))
  
  (defclass factored-cloud-shared-chunk (chunk) ())
  
  (defmethod make-old-nodes ((chunk factored-cloud-shared-chunk))
    (nodes chunk))
  
  (defmethod initialize-instance :after ((cloud factored-cloud) &key rank
                                         &allow-other-keys)
  