network unknown {
}
variable X1 {
  type discrete [ 2 ] { a, b };
}
variable X2 {
  type discrete [ 2 ] { c, d };
}
variable X3 {
  type discrete [ 2 ] { e, f };
}
variable X4 {
  type discrete [ 2 ] { g, h };
}
probability ( X1 ) {
  table 0.53, 0.47;
}
probability ( X2 ) {
  table 0.34, 0.66;
}
probability ( X3 | X1, X2 ) {
  (a, c) 0.15, 0.85;
  (b, c) 0.4, 0.6;
  (a, d) 0.75, 0.25;
  (b, d) 0.8, 0.2;
}
probability ( X4 | X3 ) {
  (e) 0.2, 0.8;
  (f) 0.42, 0.58;
}
