strict digraph sbox3 {
  x0  -> t01; x2  -> t01;  // t01 = x0  ^ x2;
  x0  -> t02; x3  -> t02;  // t02 = x0  | x3;
  x0  -> t03; x3  -> t03;  // t03 = x0  & x3;
  t01 -> t04; t02 -> t04;  // t04 = t01 & t02;
  x1  -> t05; t03 -> t05;  // t05 = x1  | t03;
  x0  -> t06; x1  -> t06;  // t06 = x0  & x1;
  x3  -> t07; t04 -> t07;  // t07 = x3  ^ t04;
  x2  -> t08; t06 -> t08;  // t08 = x2  | t06;
  x1  -> t09; t07 -> t09;  // t09 = x1  ^ t07;
  x3  -> t10; t05 -> t10;  // t10 = x3  & t05;
  t02 -> t11; t10 -> t11;  // t11 = t02 ^ t10;
  t08 -> y3;  t09 -> y3;   // y3  = t08 ^ t09;
  x3  -> t13; y3  -> t13;  // t13 = x3  | y3;
  x0  -> t14; t07 -> t14;  // t14 = x0  | t07;
  x1  -> t15; t13 -> t15;  // t15 = x1  & t13;
  t08 -> y2;  t11 -> y2;   // y2  = t08 ^ t11;
  t14 -> y0;  t15 -> y0;   // y0  = t14 ^ t15;
  t05 -> y1;  t04 -> y1;   // y1  = t05 ^ t04;
}