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 The Swiss Army Knife of Meaning Representation

This repository provides software to support participants in the shared tasks on Meaning Representation Parsing (MRP) at the 2019 and 2020 Conference on Computational Natural Language Learning (CoNLL).

Please see the above task web site for additional background.


mtool implements the official MRP 2019 cross-framwork metric, as well as a range of framework-specific graph similarity metrics, viz.

The ‘official’ cross-framework metric for the MRP 2019 shared task is a generalization of the framework-specific metrics, considering all applicable ‘pieces of information’ (i.e. tuples representing basic structural elements) for each framework:

  1. top nodes;
  2. node labels;
  3. node properties;
  4. node anchoring;
  5. directed edges;
  6. edge labels; and
  7. edge attributes.

When comparing two graphs, node-to-node correspondences need to be established (via a potentially approximative search) to maximize the aggregate, unweighted score of all of the tuple types that apply for each specific framework. Directed edges and edge labels, however, are always considered in conjunction during this search.

./ --read mrp --score mrp --gold data/sample/eds/wsj.mrp data/score/eds/
{"n": 87,
 "tops": {"g": 87, "s": 87, "c": 85, "p": 0.9770114942528736, "r": 0.9770114942528736, "f": 0.9770114942528736},
 "labels": {"g": 2500, "s": 2508, "c": 2455, "p": 0.9788676236044657, "r": 0.982, "f": 0.9804313099041533},
 "properties": {"g": 262, "s": 261, "c": 257, "p": 0.9846743295019157, "r": 0.9809160305343512, "f": 0.982791586998088},
 "anchors": {"g": 2500, "s": 2508, "c": 2430, "p": 0.9688995215311005, "r": 0.972, "f": 0.9704472843450479},
 "edges": {"g": 2432, "s": 2439, "c": 2319, "p": 0.95079950799508, "r": 0.9535361842105263, "f": 0.952165879696161},
 "attributes": {"g": 0, "s": 0, "c": 0, "p": 0.0, "r": 0.0, "f": 0.0},
 "all": {"g": 7781, "s": 7803, "c": 7546, "p": 0.9670639497629117, "r": 0.9697982264490426, "f": 0.9684291581108829}}

Albeit originally defined for one specific framework (EDS, DM and PSD, AMR, or UCCA, respectively), the pre-MRP metrics are to some degree applicable to other frameworks too: the unified MRP representation of semantic graphs enables such cross-framework application, in principle, but this functionality remains largely untested (as of June 2019).

The Makefile in the data/score/ sub-directory shows some example calls for the MRP scorer. As appropriate (e.g. for comparison to third-party results), it is possible to score graphs in each framework using its ‘own’ metric, for example (for AMR and UCCA, respectively):

./ --read mrp --score smatch --gold data/score/amr/test1.mrp data/score/amr/test2.mrp 
{"n": 3, "g": 30, "s": 29, "c": 24, "p": 0.8, "r": 0.8275862068965517, "f": 0.8135593220338982}
./ --read mrp --score ucca --gold data/score/ucca/ data/score/ucca/ewt.tupa.mrp 
{"n": 3757,
   {"primary": {"g": 63720, "s": 62876, "c": 38195,
                "p": 0.6074654876264394, "r": 0.5994193345888261, "f": 0.6034155897500711},
    "remote": {"g": 2673, "s": 1259, "c": 581,
               "p": 0.4614773629864972, "r": 0.21735877291432848, "f": 0.2955239064089522}},
   {"primary": {"g": 56114, "s": 55761, "c": 52522,
                "p": 0.9419128064417783, "r": 0.9359874541112735, "f": 0.938940782122905},
    "remote": {"g": 2629, "s": 1248, "c": 595,
               "p": 0.47676282051282054, "r": 0.22632179535945227, "f": 0.3069383543977302}}}

For all scorers, the --trace command-line option will enable per-item scores in the result (indexed by frameworks and graph identifiers). For MRP and SMATCH, the --limit option controls the maximum node pairing steps or hill-climbing iterations, respectively, to attempt during the search (with defaults 500000 and 20, respectively). As of early July, 2019, the search for none-to-node correspondences in the MRP metric can be initialized from the result of the random-restart hill-climbing (RRHC) search from SMATCH. This initialization is on by default; it increases running time of the MRP scorer but yields a guarantee that the "all" counts of matching tuples in MRP will always be at least as high as the number of "c"(orrect) tuples identified by SMATCH. To control the two search steps in MRP computation separately, the --limit option can take a colon-separated pair of integers, for example 5:100000 for five hill-climbing iterations and up to 100,000 node pairing steps. Note that multi-valued use of the --limit option is only meaningful in conjunction with the MRP metric, and that setting either of the two values to 0 will disable the corresponding search component. Finally, the MRP scorer can parallelize evaluation: an option like --cores 8 (on suitable hardware) will run eight mtool processes in parallel, which should reduce scoring time substantially.


Kuhlmann & Oepen (2016) discuss a range of structural graph statistics; mtool integrates their original code, e.g.

./ --read mrp --analyze data/sample/amr/wsj.mrp 
(01)	number of graphs	87
(02)	number of edge labels	52
(03)	\percentgraph\ trees	51.72
(04)	\percentgraph\ treewidth one	51.72
(05)	average treewidth	1.494
(06)	maximal treewidth	3
(07)	average edge density	1.050
(08)	\percentnode\ reentrant	4.24
(09)	\percentgraph\ cyclic	13.79
(10)	\percentgraph\ not connected	0.00
(11)	\percentgraph\ multi-rooted	0.00
(12)	percentage of non-top roots	0.00
(13)	average edge length	--
(14)	\percentgraph\ noncrossing	--
(15)	\percentgraph\ pagenumber two	--


mtool can test high-level wellformedness and (superficial) plausiblity of MRP graphs through its emerging --validate option. The MRP validator continues to evolve, but the following is indicative of its functionality:

./ --read mrp --validate all data/validate/eds/wsj.mrp 
validate(): graph ‘20001001’: missing or invalid ‘input’ property
validate(): graph ‘20001001’; node #0: missing or invalid label
validate(): graph ‘20001001’; node #1: missing or invalid label
validate(): graph ‘20001001’; node #3: missing or invalid anchoring
validate(): graph ‘20001001’; node #6: invalid ‘anchors’ value: [{'from': 15, 'to': 23}, {'from': 15, 'to': 23}]
validate(): graph ‘20001001’; node #7: invalid ‘anchors’ value: [{'form': 15, 'to': 17}]


Among its options for format coversion, mtool supports output of graphs to the DOT language for graph visualization, e.g.

./ --id 20001001 --read mrp --write dot data/sample/eds/wsj.mrp
dot -Tpdf > 20001001.pdf

When converting from token-based file formats that may lack either the underlying ‘raw’ input string, character-based anchoring, or both, the --text command-line option will enable recovery of inputs and attempt to determine anchoring. Its argument must be a file containing pairs of identifiers and input strings, one per line, separated by a tabulator, e.g.

./ --id 20012005 --text data/sample/wsj.txt --read dm --write dot data/sample/psd/wsj.sdp

For increased readability, the --ids option will include MRP node identifiers in graph rendering, and the --strings option can replace character-based anchors with the corresponding sub-string from the input field of the graph (currently only for the DOT output format), e.g.

./ --n 1 --strings --read mrp --write dot data/sample/ucca/wsj.mrp


When scoring with the MRP metric, mtool can optionally provide a per-item breakdown of differences between the gold and the system graphs, i.e. record false negatives (‘missing’ tuples) and false positives (‘surplus’ ones). This functionality is activated via the --errors command-line option, and tuple mismatches between the two graphs are recorded as a hierarchically nested JSON object, indexed (in order) by framework, item identifier, and tuple type.

For example:

./ --read mrp --score mrp --framework eds --gold data/score/lpps.mrp --errors errors.json data/score/eds/lpps.peking.mrp

For the first EDS item (#102990) in this comparison, errors.json will contain a sub-structure like the following:

{"correspondences": [[0, 0], [1, 1], [2, 3], [3, 4], [4, 5], [5, 6], [6, 7], [7, 8], [8, 9], [9, 10], [10, 11],
                     [11, 12], [12, 13], [13, 15], [14, 16], [15, 17], [16, 14], [17, 18], [18, 19], [19, 20]],
 "labels": {"missing": [[2, "_very+much_a_1"]],
            "surplus": [[3, "_much_x_deg"], [2, "_very_x_deg"]]},
 "anchors": {"missing": [[2, [6, 7, 8, 9, 11, 12, 13, 14]]],
             "surplus": [[2, [6, 7, 8, 9]], [3, [11, 12, 13, 14]]]},
 "edges": {"surplus": [[2, 3, "arg1"]]}}

When interpreting this structure, there are (of course) two separate spaces of node identifiers; the correspondences vector records the (optimal) node-to-node relation found by the MRP scorer, pairing identifiers from the gold graph with corresponding identifiers in the system graph. In the above, for example, gold node #2 corresponds to system node #3, and there is a spurious node #2 in the example system graph, which does not correspond to any of the gold nodes. Node identifiers in "missing" entries refer to gold nodes, whereas identifiers in "surplus" entries refer to the system graph, and they may or may not stand in a correspondence relation to a gold node.

The differences between these two graphs can be visualized as follows, color-coding false negatives in red, and false positives in blue (and using gold identifiers, where available).

sample visualization

Common Options

The --read and --write command-line options determine the input and output codecs to use. Valid input arguments include mrp, amr, ccd, dm, eds, pas, psd, ud, eud, and ucca; note that some of these formats are only partially supported. The range of supported output codecs includes mrp, dot, or txt.

The optional --id, --i, or --n options control which graph(s) from the input file(s) to process, selecting either by identifier, by (zero-based) position into the sequence of graphs read from the file, or using the first n graphs. These options cannot be combined with each other and take precendence over each other in the above order.

Another way of selecting only a subset of graphs (from both the gold and system inputs) is the --framework option, which will limit the selection to graphs with matching "framework" values. Finally, the --unique option will discard graphs with multiple occurences of the same identifier, keeping only the first occurence from the input stream.

Most top-level graph properties ("id", "time", "source", "provenance", "language", "flavor", "framework", "targets", "input") can be set (or destructively overwritten, upon completion of input processing) using the --inject option, which takes as its argument a JSON object, e.g.

./ --text wsj.txt --read eds \
  --inject '{"source": "wsj", "provenance": "Redwoods Ninth Growth (ERG 1214)"}' \
  --write mrp wsj.eds wsj.mrp


You can install mtool via pip with the following command:

pip install git+



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