diff --git a/tables/dump-parsers/convert-to-prefix.py b/tables/dump-parsers/convert-to-prefix.py
new file mode 100755
index 0000000..af408c6
--- /dev/null
+++ b/tables/dump-parsers/convert-to-prefix.py
@@ -0,0 +1,141 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""Convert LispTree formulas to Prefix encoding.
+
+Assume implicit join.
+Skip formulas that cannot be converted.
+
+If the file is tab-separated, only process the first column.
+"""
+
+import sys, os, shutil, re, argparse, json, gzip
+from codecs import open
+from itertools import izip
+from collections import defaultdict
+
+import fileinput
+import lisptree
+
+NUMBER_PREFIX = 'N'
+DATE_PREFIX = 'D'
+TYPE_ROW = 'type-row'
+AGGREGATE = ['count', 'min', 'max', 'sum', 'avg']
+MERGE_ARITH = ['and', 'or', '-']
+SUPERLATIVE = ['argmin', 'argmax']
+
+def convert(tree, args):
+    answer = []
+    def recurse(subtree):
+        if isinstance(subtree, basestring):
+            answer.append(subtree)
+            return
+        if isinstance(subtree[0], basestring):
+            opr = subtree[0]
+            if opr in AGGREGATE:
+                assert len(subtree) == 2, str(subtree)
+                answer.append(opr)
+                recurse(subtree[1])
+            elif opr in MERGE_ARITH:
+                assert len(subtree) == 3, str(subtree)
+                if opr == '-':
+                    opr = 'diff'
+                answer.append(opr)
+                recurse(subtree[1])
+                recurse(subtree[2])
+            elif opr in SUPERLATIVE:
+                assert len(subtree) in (3, 5), str(subtree)
+                if len(subtree) == 3:
+                    u, b = subtree[1], subtree[2]
+                else:
+                    u, b = subtree[3], subtree[4]
+                assert b[0] == 'reverse'
+                assert b[1][0] == 'lambda'
+                answer.append(opr)
+                recurse(u)
+                recurse(b[1][2])
+            elif opr == 'lambda':
+                assert False, 'Cannot convert lambda'
+                #assert len(subtree) == 3, str(subtree)
+                #answer.append(opr)
+                #recurse(subtree[2])
+            elif opr == 'reverse':
+                assert False, 'Cannot convert reverse'
+                #assert len(subtree) == 2, str(subtree)
+                #answer.append(opr)
+                #recurse(subtree[1])
+            elif opr == 'var':
+                assert len(subtree) == 2, str(subtree)
+                answer.append(subtree[1])
+            elif opr == 'number':
+                assert len(subtree) == 2, str(subtree)
+                answer.append(NUMBER_PREFIX + subtree[1])
+            elif opr == 'date':
+                assert len(subtree) == 4, str(subtree)
+                answer.append(DATE_PREFIX + '-'.join(
+                    'XX' if x == '-1' else x for x in subtree[1:4]))
+            else:    # Join with a name
+                assert len(subtree) == 2, str(subtree)
+                if ('fb:type.object.type' == opr and
+                        'fb:type.row' == subtree[1]):
+                    answer.append(TYPE_ROW)
+                else:
+                    answer.append(opr)
+                    recurse(subtree[1])
+        else:   # Join with a complex construct
+            assert len(subtree) == 2, str(subtree)
+            # Only allows ((reverse ...) ...)
+            assert subtree[0][0] == 'reverse', str(subtree)
+            assert len(subtree[0]) == 2, str(subtree)
+            answer.append('!' + subtree[0][1])
+            recurse(subtree[1])
+    recurse(tree)
+    return answer
+
+def prenormalize(lf, args):
+    lf = lf[:]
+    # Mark all normalization relations
+    for i in xrange(len(lf)):
+        if lf[i].startswith('fb:cell.cell.'):
+            assert lf[i-1].startswith('fb:row.row.')
+            lf[i-1] = 'fb:row.{}.{}'.format(
+                    lf[i][len('fb:cell.cell.'):],
+                    lf[i-1][len('fb:row.row.'):])
+            lf[i] = ''
+        elif lf[i].startswith('!fb:cell.cell.'):
+            assert lf[i+1].startswith('!fb:row.row.')
+            lf[i+1] = '!fb:row.{}.{}'.format(
+                    lf[i][len('!fb:cell.cell.'):],
+                    lf[i+1][len('!fb:row.row.'):])
+            lf[i] = ''
+    return [x for x in lf if x]
+
+def process(line, args):
+    line = line.rstrip('\n').split('\t')
+    lf = lisptree.parse(line[args.field])
+    lf = convert(lf, args)
+    lf = prenormalize(lf, args)
+    line[args.field] = ' '.join(lf)
+    print '\t'.join(line)
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('-f', '--field', type=int, default=0,
+            help='Field index (tab-separated; 0-based) containing the logical form')
+    parser.add_argument('infile')
+    args = parser.parse_args()
+
+    if args.infile != '-':
+        opener = gzip.open if args.infile.endswith('.gz') else open 
+        with opener(args.infile, 'r', 'utf8') as fin:
+            for line in fin:
+                process(line, args)
+    else:
+        for line in sys.stdin:
+            try:
+                process(line, args)
+            except Exception as e:
+                print >> sys.stderr, 'ERROR:', line.rstrip()
+
+if __name__ == '__main__':
+    main()
+