In the study of path-finding problems in artificial intelligence, a heuristic function is said to be consistent, or monotone, if its estimate is always less than or equal to the estimated distance from any neighbouring vertex to the goal, plus the cost of reaching that neighbour.
Bibliography
“Consistent Heuristic.” 2022. Wikipedia, October. https://en.wikipedia.org/w/index.php?title=Consistent_heuristic&oldid=1116114302.