private InferenceParameter getInferenceParameter(CycSymbol parameterName) throws RuntimeException {
    InferenceParameterDescriptions descriptions = getDefaultInferenceParameterDescriptions();
    if (descriptions == null) {
      throw new RuntimeException("Cannot find inference parameter descriptions");
    }
    InferenceParameter param = (InferenceParameter) descriptions.get(parameterName);
    if (param == null) {
      throw new RuntimeException("No parameter found by name " + parameterName);
    }
    return param;
  }