unambiguous

An LR(k) grammar is clearly unambiguous, since the definition implies every derivation tree must have the same handle, and by induction there is only one possible tree. It is interesting to point out furthermore that nearly every grammar which is known to be unambiguous is either an LR(k) grammar, or (dually) is a right-to-left translatable grammar, or is some grammar which is translated using "both ends toward the middle." Thus, the LR(k) condition may be regarded as the most powerful general test for nonambiguity that is now available.