Uncertainty, page 18 CSI 4106, Winter 2005 Truth maintenance (3) A new rule and a new fact: happy(b)  happy(c) happy(d) happy(a) truth value: TRUE justification: given      happy (a)  happy(b) truth value: TRUE justification: given happy(b) truth value: TRUE justification: deduced happy (b)  happy(c) truth value: TRUE justification: given happy(c) truth value: TRUE justification: deduced      happy(d) truth value: TRUE justification: given