This the s is pres ents a sy st em for underst an ding natura l langu a ge. By un der s tandi ng, I me an the as signment of me aning stru ct ur es to pi ec es of n at ur al la nguage texts. The part i cu la r me an ing s tru ct ur es th at we u se will be explaine d l at er, but for the moment ass ume th at me an ing stru ctu res are symbo licre pres ent at i on sof the con cepts un der lying l an gul a ge. Comput ati on al underst an di ng, asde fin edhe re, is the extraction of con ceptual s tructures from in put texts. The the s is cons ists of two parts. Part I is about a pro gram for th e me an ing an a lys isofsentences. Th epro gram assigns me an ings tru cturestoawi de ra ngeofs ente nces. Typ icalof the class of se n te ncesh and led are the following: John gave Mary abeating.