A finite basis of the set of all monotone partial functions defined over a finite poset

Let X be an arbitrary poset. A partial function f with n variables defined over X is said to be monotone if the following condition is satisfied: if x/sub 1//spl les/y/sub 1/,..., x/sub m//spl les/y/sub n/, and both the values f(x/sub 1/,..., x/sub n/) and f(y/sub 1/,....y/sub n/) are defined, then f(x/sub 1/,..., x/sub n/)/spl les/f(y/sub 1/,...,y/sub n/) It is shown that the set of all monotone partial functions has a finite basis.