The production in RFC 4122 (section 3, page 4), defines UUID string representation as
UUID = time-low "-" time-mid "-"
time-high-and-version "-"
clock-seq-and-reserved
clock-seq-low "-" node
where each internal component is hex-encoded.
Therefore, f47ac10b58cc4372a5670e02b2c3d479 is not a valid UUID representation.