Evaluating XPath Expresssions

XPath Result of XPath Evaluation
if (matches('abcabc', '(a b c)+')) then 'Success'else 'Failure'
Failure
if (matches('abcabc', '(a b c)+', 'x')) then 'Success'else 'Failure'
Success
if (matches('a b c a b c', '(a b c)+', 'x')) then 'Success'else 'Failure'
Failure