code: private double getLogProductOfAllFalseMessages(VarTensor[] inMsgs) {
          // Precompute the product of all the "false" messages.
          // pi = \prod_i \mu_i(0)
          // Here we store log pi.
          Algebra s = inMsgs[0].getAlgebra();
          double logPi = 0.0;
          for (VarTensor inMsg : inMsgs) {
              logPi += s.toLogProb(inMsg.getValue(LinkVar.FALSE));
          }
          return logPi;
      }
docs: Computes pi = \prod_i \mu_i(0).