Tregex Patterns

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Symbol Meaning
A << B A dominates B
A >> B A is dominated by B
A < B A immediately dominates B
A > B A is immediately dominated by B
A $ B A is a sister of B (and not equal to B)
A .. B A precedes B
A . B A immediately precedes B
A ,, B A follows B
A , B A immediately follows B
A <<, B B is a leftmost descendant of A
A <<- B B is a rightmost descendant of A
A >>, B A is a leftmost descendant of B
A >>- B A is a rightmost descendant of B
A <, B B is the first child of A
A >, B A is the first child of B
A <- B B is the last child of A
A >- B A is the last child of B
A <` B B is the last child of A
A >` B A is the last child of B
A <i B B is the ith child of A (i > 0)
A >i B A is the ith child of B (i > 0)
A <-i B B is the ith-to-last child of A (i > 0)
A >-i B A is the ith-to-last child of B (i > 0)
A <: B B is the only child of A
A >: B A is the only child of B
A <<: B A dominates B via an unbroken chain (length > 0) of unary local trees.
A >>: B A is dominated by B via an unbroken chain (length > 0) of unary local trees.
A $++ B A is a left sister of B (same as $.. for context-free trees)
A $– B A is a right sister of B (same as $,, for context-free trees)
A $+ B A is the immediate left sister of B (same as $. for context-free trees)
A $- B A is the immediate right sister of B (same as $, for context-free trees)
A $.. B A is a sister of B and precedes B
A $,, B A is a sister of B and follows B
A $. B A is a sister of B and immediately precedes B
A $, B A is a sister of B and immediately follows B
A <+(C) B A dominates B via an unbroken chain of (zero or more) nodes matching description C
A >+(C) B A is dominated by B via an unbroken chain of (zero or more) nodes matching description C
A .+(C) B A precedes B via an unbroken chain of (zero or more) nodes matching description C
A ,+(C) B A follows B via an unbroken chain of (zero or more) nodes matching description C
A <<# B B is a head of phrase A
A >># B A is a head of phrase B
A <# B B is the immediate head of phrase A
A ># B A is the immediate head of phrase B
A == B A and B are the same node
A <= B A and B are the same node or A is the parent of B
A : B [this is a pattern-segmenting operator that places no constraints on the relationship between A and B]
A <… { B ; C ; … } A has exactly B, C, etc as its subtree, with no other children.

Source: https://nlp.stanford.edu/nlp/javadoc/javanlp/edu/stanford/nlp/trees/tregex/TregexPattern.html

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