5.1 Example 1 5.2 Example 2 5.3 Example 3 5.4 Example 4 5.5 Example 5 6 See also 7 References 8 External links Introduction While Natural language (NL) can be vague and ambiguous, ERROL ( Markowitz and Raz 1983a ) is accurate with well-defined semantics, and thus provides a check for NL