Put a fronted WHADVP back in the predicate of an empty copula

"How are you?" and "I know where he is" came out with the copula as
the head and the wh-adverb as advmod.  EWT and GUM make the wh-adverb
the head of its copular clause when the copula has no other
predicate, as in "How was your trip", "When is the wedding?" or
"asked how the food was".

As for a fronted WHADJP, move the WHADVP to the copula, relabeled as
an ADVP, when the copula has nothing after it.  In a main clause
question with no VP, where the SQ is just the copula and the subject,
the adverb goes after the subject, the same shape as "Is the trouble
over?".  The adverb is then the head of the clause, with the copula
as cop:

    Where is the station?          Where head, is cop, station nsubj
    When will the meeting be?      When head, will aux, be cop
    I know where he is             ccomp(know, where), is cop

A WHADVP is usually an adjunct, so the move needs a copula with
nothing at all after it: "Where are you going?", "Why is he here?"
and "when it was late" are unchanged.

The relation rules tell a where or when complement, as in "I know
where he is", from an adjunct, as in "stay where we are" or "put your
money where your mouth is", by the WHADVP at the start of the SBAR.
The move takes that away, so it is limited to the clauses whose
relation does not depend on it: the complement of a verb which takes a
wh-clause, the object of a preposition, as in "back to where she was",
a clause with how, and a main clause question.  The adjunct clauses
are unchanged.  A WRB at the end of the ADVP it is moved as is its head,
so "know just where it was" has where as the head, with just as
advmod.  The PTB sometimes writes "how terrific" or "how useful" as a
WHADVP, and there the adjective is still the head.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FFFrVzJ9BaKtDx4UPVveJx

Author: AngledLuffa

src/edu/stanford/nlp/trees/CoordinationTransformer.java

@@ -127,6 +127,11 @@ public Tree transformTree(Tree t) {
       debugLine("After moveWHADJPToCopula:         ", t);
     }
 
+    t = moveWHADVPToCopula(t);
+    if (VERBOSE) {
+      debugLine("After moveWHADVPToCopula:         ", t);
+    }
+
     if (performMWETransformation) {
       t = MWETransform(t);
       if (VERBOSE) {
@@ -242,6 +247,56 @@ public static Tree moveWHADJPToCopula(Tree t) {
     return Tsurgeon.processPattern(moveWHADJPTregex, moveWHADJPTsurgeon, t);
   }
 
+  // A fronted WHADVP whose clause has a copula with no predicate, as in
+  // "I know where he is", "How was your trip?" or "When will the
+  // meeting be?"  Unlike a WHADJP, a WHADVP is usually an adjunct, so
+  // the copula must have nothing else after it, not even an adverb or a
+  // PP, as in "why is he here" or "where is he from".
+  private static final String WHADVP_EMPTY_COPULA =
+    "(WHADVP=wh $+ (S|SQ <+(VP|S|SQ) (VP=vp < (/^VB/=cop < " + EnglishPatterns.copularWordRegex + ") !< NP|ADJP|ADVP|PRT|PP|VP|UCP|S|SBAR|WHADJP)))";
+
+  // The relation rules tell a where or when complement, as in "I know
+  // where he is", from an adjunct, as in "stay where we are" or "put
+  // your money where your mouth is", by the WHADVP at the start of the
+  // SBAR.  The move takes that away, so it is limited to the places
+  // where the relation of the clause does not depend on it: the
+  // complement of a verb which takes a wh-clause, the object of a
+  // preposition, a clause with how, and a main clause question.
+  private static final TregexPattern moveWHADVPTregex =
+    TregexPattern.compile("SBAR [ > (VP < (/^V/ < " + EnglishPatterns.ccompVerbRegex + ") < (/^V/ < " + EnglishPatterns.ccompObjVerbRegex + ")) | " +
+                          "!$-- NP > (VP < (/^V/ < " + EnglishPatterns.ccompVerbRegex + ")) | > PP | " +
+                          "!$-- NP <, (WHADVP < (WRB < /^(?i:how)$/)) ] < " + WHADVP_EMPTY_COPULA);
+
+  private static final TregexPattern moveWHADVPQuestionTregex =
+    TregexPattern.compile("SBARQ < " + WHADVP_EMPTY_COPULA);
+
+  private static final TsurgeonPattern moveWHADVPTsurgeon =
+    Tsurgeon.parseOperation("[move wh $- cop] [relabel wh ADVP]");
+
+  // The same in a main clause question with no VP, where the SQ is just
+  // the copula and the subject, as in "Where is the station?"  The
+  // adverb goes after the subject, as in "Is the station here?"
+  private static final TregexPattern moveWHADVPSQTregex =
+    TregexPattern.compile("SBARQ < (WHADVP=wh $+ (SQ=sq <, (/^VB/ < " + EnglishPatterns.copularWordRegex + ") <- NP !<3 __))");
+
+  private static final TsurgeonPattern moveWHADVPSQTsurgeon =
+    Tsurgeon.parseOperation("[move wh >-1 sq] [relabel wh ADVP]");
+
+  /**
+   * Puts a fronted wh-adverb back in the predicate position of a copula
+   * which has no predicate, as in "I know where he is" or "Where is the
+   * station?"  After the move, the adverb is the head of the copular
+   * clause, with the copula as cop, as in UD.
+   */
+  public static Tree moveWHADVPToCopula(Tree t) {
+    if (t == null) {
+      return null;
+    }
+    t = Tsurgeon.processPattern(moveWHADVPTregex, moveWHADVPTsurgeon, t);
+    t = Tsurgeon.processPattern(moveWHADVPQuestionTregex, moveWHADVPTsurgeon, t);
+    return Tsurgeon.processPattern(moveWHADVPSQTregex, moveWHADVPSQTsurgeon, t);
+  }
+
   /** The basic category of a label, without function tags such as -TMP */
   private static String category(Tree t) {
     String label = t.value();

src/edu/stanford/nlp/trees/UniversalEnglishGrammaticalRelations.java

@@ -177,7 +177,7 @@ private UniversalEnglishGrammaticalRelations() {}
 
   /** An adverb which the head finder can make the predicate of a copula */
   private static final String COPULAR_ADVERB =
-    "(/^(?:ADVP|PRT)/ < (/^(?:RB|RP|IN|NN|JJ)/ < " + UniversalSemanticHeadFinder.COPULAR_ADVERB_REGEX + "))";
+    "(/^(?:ADVP|PRT)/ < (/^(?:RB|RP|IN|NN|JJ|WRB)/ < " + UniversalSemanticHeadFinder.COPULAR_ADVERB_REGEX + "))";
 
   /**
    * The "copula" grammatical relation.  A copula is the relation between

src/edu/stanford/nlp/trees/UniversalSemanticHeadFinder.java

@@ -304,15 +304,17 @@ protected int postOperationFix(int headIdx, Tree[] daughterTrees) {
 
   /**
    * Adverbs of place and direction which can be the predicate of a
-   * copula, as in "he is here" or "the game is over".  Other adverbs
+   * copula, as in "he is here" or "the game is over", and wh-adverbs
+   * moved back after a copula, as in "I know where he is".  Other adverbs
    * after a copula, as in "the goal is simply to win", are modifiers.
    * "ago" is left out, since "it was a year ago" is most often an
    * ellipsis, as in "higher than it was a year ago".
    */
   static final String COPULAR_ADVERB_REGEX = "/^(?i:here|there|everywhere|anywhere|somewhere|nowhere|elsewhere|" +
     "above|below|ahead|behind|around|away|back|close|near|nearby|down|up|uphill|downhill|upstairs|downstairs|" +
     "in|inside|indoors|out|outside|outdoors|off|on|over|through|together|home|abroad|overseas|aboard|along|apart|aside|" +
-    "east|west|north|south|forward|far|farther|further|underway)$/";
+    "east|west|north|south|forward|far|farther|further|underway|" +
+    "where|how|when|why|wherever|whenever)$/";
 
   /**
    * A predicate adverb followed by a measure phrase or a degree adverb,
@@ -338,7 +340,7 @@ protected int postOperationFix(int headIdx, Tree[] daughterTrees) {
 
   /** An ADVP or PRT which is the predicate of a copula with no other predicate */
   static final TregexPattern copularAdverbTregex =
-    TregexPattern.compile("/^(?:ADVP|PRT)/ < (/^(?:RB|RP|IN|NN|JJ)/ < " + COPULAR_ADVERB_REGEX + ")");
+    TregexPattern.compile("/^(?:ADVP|PRT)/ < (/^(?:RB|RP|IN|NN|JJ|WRB)/ < " + COPULAR_ADVERB_REGEX + ")");
 
   /**
    * We use this to avoid making a -TMP or -ADV the head of a copular phrase.
@@ -385,6 +387,14 @@ protected Tree determineNonTrivialHead(Tree t, Tree parent) {
       if (matcher.matchesAt(t)) {
         return matcher.getNode("head");
       }
+      // a wh-adverb moved back after a copula is the head of its ADVP
+      // when it comes last, as in "know just where it was".  In "how
+      // terrific they are" or "how useful it is", the head is the
+      // adjective, as for any other ADVP
+      Tree lastKid = t.lastChild();
+      if (lastKid.value().equals("WRB")) {
+        return lastKid;
+      }
     }
 
     if (motherCat.equals("CONJP")) {

test/src/edu/stanford/nlp/trees/UniversalEnglishGrammaticalStructureTest.java

@@ -722,6 +722,61 @@ public static Collection<Object[]> testCases() {
            "root(ROOT-0, investigating-4)\n" +
            "det(causes-6, the-5)\n" +
            "obj(investigating-4, causes-6)\n"},
+         // a fronted wh-adverb is the predicate of an empty copula
+         {TestType.BASIC,
+          "(ROOT (SBARQ (WHADVP (WRB Where)) (SQ (VBZ is) (NP (DT the) (NN station))) (. ?)))",
+          "root(ROOT-0, Where-1)\n" +
+           "cop(Where-1, is-2)\n" +
+           "det(station-4, the-3)\n" +
+           "nsubj(Where-1, station-4)\n"},
+         {TestType.BASIC,
+          "(ROOT (S (NP (PRP I)) (VP (VBP know) (SBAR (WHADVP (WRB where)) (S (NP (PRP he)) (VP (VBZ is))))) (. .)))",
+          "nsubj(know-2, I-1)\n" +
+           "root(ROOT-0, know-2)\n" +
+           "ccomp(know-2, where-3)\n" +
+           "nsubj(where-3, he-4)\n" +
+           "cop(where-3, is-5)\n"},
+         {TestType.BASIC,
+          "(ROOT (S (NP (PRP We)) (VP (VBD knew) (SBAR (WHADVP (RB just) (WRB where)) (S (NP (PRP it)) (VP (VBD was))))) (. .)))",
+          "nsubj(knew-2, We-1)\n" +
+           "root(ROOT-0, knew-2)\n" +
+           "advmod(where-4, just-3)\n" +
+           "ccomp(knew-2, where-4)\n" +
+           "nsubj(where-4, it-5)\n" +
+           "cop(where-4, was-6)\n"},
+         // how with an adjective in a WHADVP has the adjective as the head
+         {TestType.BASIC,
+          "(ROOT (S (NP (PRP We)) (VP (VBP know) (SBAR (WHADVP (WRB how) (JJ useful)) (S (NP (PRP it)) (VP (VBZ is))))) (. .)))",
+          "nsubj(know-2, We-1)\n" +
+           "root(ROOT-0, know-2)\n" +
+           "advmod(useful-4, how-3)\n" +
+           "ccomp(know-2, useful-4)\n" +
+           "nsubj(useful-4, it-5)\n" +
+           "cop(useful-4, is-6)\n"},
+         // an adjunct where clause keeps the copula as its head
+         {TestType.BASIC,
+          "(ROOT (S (NP (NNS Rates)) (VP (MD will) (VP (VB stay) (SBAR (WHADVP (WRB where)) (S (NP (PRP they)) (VP (VBP are)))))) (. .)))",
+          "nsubj(stay-3, Rates-1)\n" +
+           "aux(stay-3, will-2)\n" +
+           "root(ROOT-0, stay-3)\n" +
+           "advmod(are-6, where-4)\n" +
+           "nsubj(are-6, they-5)\n" +
+           "advcl(stay-3, are-6)\n"},
+         // a wh-adverb with a verb or another predicate stays an adjunct
+         {TestType.BASIC,
+          "(ROOT (SBARQ (WHADVP (WRB Where)) (SQ (VBP are) (NP (PRP you)) (VP (VBG going))) (. ?)))",
+          "advmod(going-4, Where-1)\n" +
+           "aux(going-4, are-2)\n" +
+           "nsubj(going-4, you-3)\n" +
+           "root(ROOT-0, going-4)\n"},
+         {TestType.BASIC,
+          "(ROOT (S (NP (PRP I)) (VP (VBP know) (SBAR (WHADVP (WRB when)) (S (NP (PRP it)) (VP (VBD was) (ADJP (JJ late)))))) (. .)))",
+          "nsubj(know-2, I-1)\n" +
+           "root(ROOT-0, know-2)\n" +
+           "advmod(late-6, when-3)\n" +
+           "nsubj(late-6, it-4)\n" +
+           "cop(late-6, was-5)\n" +
+           "ccomp(know-2, late-6)\n"},
          {TestType.BASIC,
           "(ROOT (SBARQ (WHPP (IN In) (WHNP (WDT which) (NN city))) (SQ (VBP do) (NP (PRP you)) (VP (VB live))) (. ?)))",
           "case(city-3, In-1)\n" +