using System;

using System.Text.RegularExpressions;

​

public class Example

{

    public static void Main()

    {

        string pattern = @"(?<statement>(?<word>\w+)+\s+(With|Without)\s+(?<-word>\w+)+(?(word)(?!)))|(?<statement>\sAND\s)|(?<remainder>\sAND$)";

        string input = @" Tom With Jane AND Mike Without Anne AND";

        foreach (Match m in Regex.Matches(input, pattern))

        {

            Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);

        }

    }

}