Ordered that the order is reversed, on the law, with costs, the petition is denied, and the cross application to confirm is granted.
The arbitrator's conclusion that the termination of William Gray as a probationary teacher violated the subject collective bargaining agreement was entirely rational and did not constitute a rewriting of that agreement (see, Matter of Town of Callicoon [Civil Serv. Empls. Assn.], 70 N.Y.2d 907; Matter of Local Div. 1179 [Green Bus Lines], 50 N.Y.2d 1007; Matter of West Babylon Union Free School Dist. v. West Babylon Teachers' Assn., 237 A.D.2d 615; Matter of Dutchess Bldg. Renovations. v. Immerblum, 198 A.D.2d 413; Matter of East Ramapo Teachers Assn. v. East Ramapo Cent. School Dist., 191 A.D.2d 696). Moreover, the unsubstantiated assertion of the Board of Education of the Hempstead Union Free School District (hereinafter the Board) that the arbitrator erred as to the date upon which Gray's fourth year of probationary employment commenced provides no basis for vacatur, since it is axiomatic that "an arbitrator's award "will not be vacated for errors of law and fact committed by the arbitrator" (Matter of Sprinzen [Nomberg], 46 N.Y.2d 623, 629).
The Board's contention that the award is violative of public policy is improperly raised for the first time on appeal (see, Matter of County of Suffolk v. Faculty Assn., 247 A.D.2d 472) and, in any event, is without "merit (see generally, Matter of Sprinzen [Nomberg], supra; Matter of Cohoes City School Dist. v. Cohoes Teachers Assn., 40 N.Y.2d 774; Board of Educ. v. Bellmore-Merrick United Secondary Teachers, 39 N.Y.2d 167).
Sullivan, J.P., Joy, Krausman and Florio, JJ., concur.