ABSTRACT
Our second app l ica t ion deals w i th t h e w e l l - k n o w n c o r re sp o n d e n ce b e tw ee n c o n te x t - f r e e languages an d t r e e a u t o m a t a . The e n r i c h e d c a te g o ry t h e o r y (i.e. r e l a t io n a l presheaf) approach to t ree a u to m a t a , toge ther w i th Walters ' categorical t r e a t m e n t of context-free languages [W2], [W3] will m a k e th is co rrespondence clear , as well as prov ide simple proofs.
