{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,8,6]],"date-time":"2025-08-06T12:37:22Z","timestamp":1754483842219},"reference-count":61,"publisher":"MIT Press - Journals","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2021,2,1]]},"abstract":"<jats:title>Abstract<\/jats:title>\n               <jats:p>Formation of stimulus equivalence classes has been recently modeled through equivalence projective simulation (EPS), a modified version of a projective simulation (PS) learning agent. PS is endowed with an episodic memory that resembles the internal representation in the brain and the concept of cognitive maps. PS flexibility and interpretability enable the EPS model and, consequently the model we explore in this letter, to simulate a broad range of behaviors in matching-to-sample experiments. The episodic memory, the basis for agent decision making, is formed during the training phase. Derived relations in the EPS model that are not trained directly but can be established via the network's connections are computed on demand during the test phase trials by likelihood reasoning. In this letter, we investigate the formation of derived relations in the EPS model using network enhancement (NE), an iterative diffusion process, that yields an offline approach to the agent decision making at the testing phase. The NE process is applied after the training phase to denoise the memory network so that derived relations are formed in the memory network and retrieved during the testing phase. During the NE phase, indirect relations are enhanced, and the structure of episodic memory changes. This approach can also be interpreted as the agent's replay after the training phase, which is in line with recent findings in behavioral and neuroscience studies. In comparison with EPS, our model is able to model the formation of derived relations and other features such as the nodal effect in a more intrinsic manner. Decision making in the test phase is not an ad hoc computational method, but rather a retrieval and update process of the cached relations from the memory network based on the test trial. In order to study the role of parameters on agent performance, the proposed model is simulated and the results discussed through various experimental settings.<\/jats:p>","DOI":"10.1162\/neco_a_01346","type":"journal-article","created":{"date-parts":[[2020,11,30]],"date-time":"2020-11-30T20:04:45Z","timestamp":1606766685000},"page":"483-527","source":"Crossref","is-referenced-by-count":4,"title":["Enhanced Equivalence Projective Simulation: A Framework for Modeling Formation of Stimulus Equivalence Classes"],"prefix":"10.1162","volume":"33","author":[{"given":"Asieh Abolpou","family":"Mofrad","sequence":"first","affiliation":[{"name":"Department of Computer Science, Oslo Metropolitan University, 0130 Oslo, Norway asieh.abolpour-mofrad@oslomet.no"}]},{"given":"Anis","family":"Yazidi","sequence":"additional","affiliation":[{"name":"Department of Computer Science, Oslo Metropolitan University, 0130 Oslo, Norway Anis.Yazidi@oslomet.no"}]},{"given":"Samaneh Abolpour","family":"Mofrad","sequence":"additional","affiliation":[{"name":"Department of Computer Science, Electrical Engineering, and Mathematical Sciences, Western Norway University of Applied Sciences, 5063 Bergen, Norway, and Mohn Medical Imaging and Visualization Center, Department of Radiology, Haukeland University Hospital, 5021 Bergen, Norway Samaneh.Abolpour.Mofrad@hvl.no"}]},{"given":"Hugo L.","family":"Hammer","sequence":"additional","affiliation":[{"name":"Department of Computer Science, Oslo Metropolitan University, 0130 Oslo, Norway, and Simula Metropolitan Center, 1325 Oslo, Norway Hugo.Hammer@oslomet.no"}]},{"given":"Erik","family":"Arntzen","sequence":"additional","affiliation":[{"name":"Department of Behavioral Science, Oslo Metropolitan University, 0130 Oslo, Norway erik.arntzen@equivalence.net"}]}],"member":"281","published-online":{"date-parts":[[2021,2,1]]},"reference":[{"key":"2021031822394118000_B1","doi-asserted-by":"crossref","unstructured":"Arntzen,  E.\n           (2012). Training and testing parameters in formation of stimulus equivalence: Methodological issues. European Journal of Behavior Analysis, 13(1), 123\u2013135.","DOI":"10.1080\/15021149.2012.11434412"},{"key":"2021031822394118000_B2","doi-asserted-by":"crossref","unstructured":"Arntzen,  E., Grondahl,  T., & Eilifsen,  C. (2010). The effects of different training structures in the establishment of conditional discriminations and subsequent performance on tests for stimulus equivalence. Psychological Record, 60(3), 437\u2013461.","DOI":"10.1007\/BF03395720"},{"key":"2021031822394118000_B3","doi-asserted-by":"crossref","unstructured":"Arntzen,  E., & Hansen,  S. (2011). Training structures and the formation of equivalence classes. European Journal of Behavior Analysis, 12(2), 483\u2013503.","DOI":"10.1080\/15021149.2011.11434397"},{"key":"2021031822394118000_B4","doi-asserted-by":"crossref","unstructured":"Arntzen,  E., & Holth,  P. (1997). Probability of stimulus equivalence as a function of training design. Psychological Record, 47(2), 309\u2013320.","DOI":"10.1007\/BF03395227"},{"key":"2021031822394118000_B5","doi-asserted-by":"crossref","unstructured":"Arntzen,  E., & Mensah,  J. (2020). On the effectiveness of including meaningful pictures in the formation of equivalence classes. Journal of the Experimental Analysis of Behavior, 113(2), 305\u2013321.","DOI":"10.1002\/jeab.579"},{"key":"2021031822394118000_B6","doi-asserted-by":"crossref","unstructured":"Barnes,  D., & Hampson,  P. J. (1993). Stimulus equivalence and connectionism: Implications for behavior analysis and cognitive science. Psychological Record, 43(4), 617\u2013638.","DOI":"10.1007\/BF03395903"},{"key":"2021031822394118000_B7","doi-asserted-by":"crossref","unstructured":"Baumeister,  R. F., Bratslavsky,  E., Finkenauer,  C., & Vohs,  K. D. (2001). Bad is stronger than good. Review of General Psychology, 5(4), 323\u2013370.","DOI":"10.1037\/1089-2680.5.4.323"},{"key":"2021031822394118000_B8","doi-asserted-by":"crossref","unstructured":"Behrens,  T. E., Muller,  T. H., Whittington,  J. C., Mark,  S., Baram,  A. B., Stachenfeld,  K. L., & Kurth-Nelson,  Z. (2018). What is a cognitive map? Organizing knowledge for flexible behavior. Neuron, 100(2), 490\u2013509.","DOI":"10.1016\/j.neuron.2018.10.002"},{"key":"2021031822394118000_B9","doi-asserted-by":"crossref","unstructured":"Briegel,  H. J., & De las Cuevas,  G. (2012). Projective simulation for artificial intelligence. Scientific Reports, 2(1), 1\u201316.","DOI":"10.1038\/srep00400"},{"key":"2021031822394118000_B10","doi-asserted-by":"crossref","unstructured":"Cullinan,  V. A., Barnes,  D., Hampson,  P. J., & Lyddy,  F. (1994). A transfer of explicitly and nonexplicitly trained sequence responses through equivalence relations: An experimental demonstration and connectionist model. Psychological Record, 44(4), 559\u2013585.","DOI":"10.1007\/BF03395144"},{"key":"2021031822394118000_B11","doi-asserted-by":"crossref","unstructured":"Daw,  N. D., Gershman,  S. J., Seymour,  B., Dayan,  P., & Dolan,  R. J. (2011). Model-based influences on humans' choices and striatal prediction errors. Neuron, 69(6), 1204\u20131215.","DOI":"10.1016\/j.neuron.2011.02.027"},{"key":"2021031822394118000_B12","doi-asserted-by":"crossref","unstructured":"Daw,  N. D., Niv,  Y., & Dayan,  P. (2005). Uncertainty-based competition between prefrontal and dorsolateral striatal systems for behavioral control. Nature Neuroscience, 8(12), 1704\u20131711.","DOI":"10.1038\/nn1560"},{"key":"2021031822394118000_B13","doi-asserted-by":"crossref","unstructured":"Devany,  J. M., Hayes,  S. C., & Nelson,  R. O. (1986). Equivalence class formation in language-able and language-disabled children. Journal of the Experimental Analysis of Behavior, 46(3), 243\u2013257.","DOI":"10.1901\/jeab.1986.46-243"},{"key":"2021031822394118000_B14","doi-asserted-by":"crossref","unstructured":"Fields,  L., Adams,  B. J., Verhave,  T., & Newman,  S. (1990). The effects of nodality on the formation of equivalence classes. Journal of the Experimental Analysis of Behavior, 53(3), 345\u2013358.","DOI":"10.1901\/jeab.1990.53-345"},{"key":"2021031822394118000_B15","doi-asserted-by":"crossref","unstructured":"Fienup,  D. M., Wright,  N. A., & Fields,  L. (2015). Optimizing equivalence-based instruction: Effects of training protocols on equivalence class formation. Journal of Applied Behavior Analysis, 48(3), 613\u2013631.","DOI":"10.1002\/jaba.234"},{"key":"2021031822394118000_B16","doi-asserted-by":"crossref","unstructured":"Garvert,  M. M., Dolan,  R. J., & Behrens,  T. E. (2017). A map of abstract relational knowledge in the human hippocampal\u2013entorhinal cortex. Elife, 6, e17086.","DOI":"10.7554\/eLife.17086.021"},{"key":"2021031822394118000_B17","doi-asserted-by":"crossref","unstructured":"Groskreutz,  N. C., Karsina,  A., Miguel,  C. F., & Groskreutz,  M. P. (2010). Using complex auditory-visual samples to produce emergent relations in children with autism. Journal of Applied Behavior Analysis, 43(1), 131\u2013136.","DOI":"10.1901\/jaba.2010.43-131"},{"key":"2021031822394118000_B18","doi-asserted-by":"crossref","unstructured":"Hayes,  S. C.\n           (1989). Nonhumans have not yet shown stimulus equivalence. Journal of the Experimental Analysis of Behavior, 51(3), 385\u2013392.","DOI":"10.1901\/jeab.1989.51-385"},{"key":"2021031822394118000_B19","doi-asserted-by":"crossref","unstructured":"Hove,  O.\n           (2003). Differential probability of equivalence class formation following a one-to-many versus a many-to-one training structure. Psychological Record, 53(4), 617\u2013634.","DOI":"10.1007\/BF03395456"},{"key":"2021031822394118000_B20","doi-asserted-by":"crossref","unstructured":"Joseph,  A., & Yu,  B. (2016). Impact of regularization on spectral clustering. Annals of Statistics, 44(4), 1765\u20131791.","DOI":"10.1214\/16-AOS1447"},{"key":"2021031822394118000_B21","doi-asserted-by":"crossref","unstructured":"Kumaran,  D., & McClelland,  J. L. (2012). Generalization through the recurrent interaction of episodic memories: A model of the hippocampal system. Psychological Review, 119(3), 573\u2013616.","DOI":"10.1037\/a0028681"},{"key":"2021031822394118000_B22","doi-asserted-by":"crossref","unstructured":"Lew,  S. E., & Zanutto,  S. B. (2011). A computational theory for the learning of equivalence relations. Frontiers in Human Neuroscience, 5, 113.","DOI":"10.3389\/fnhum.2011.00113"},{"key":"2021031822394118000_B23","doi-asserted-by":"crossref","unstructured":"Lin,  L.-J.\n           (1992). Self-improving reactive agents based on reinforcement learning, planning and teaching. Machine Learning, 8(3\u20134), 293\u2013321.","DOI":"10.1007\/BF00992699"},{"key":"2021031822394118000_B24","doi-asserted-by":"crossref","unstructured":"Liu,  T.-Y., & Watson,  B. O. (2020). Patterned activation of action potential patterns during offline states in the neocortex: Replay and non-replay. Philosophical Transactions of the Royal Society B, 375(1799), 20190233.","DOI":"10.1098\/rstb.2019.0233"},{"key":"2021031822394118000_B25","doi-asserted-by":"crossref","unstructured":"Lyddy,  F., & Barnes-Holmes,  D. (2007). Stimulus equivalence as a function of training protocol in a connectionist network. Journal of Speech and Language Pathology\u2013Applied Behavior Analysis, 2(1), 14.","DOI":"10.1037\/h0100204"},{"key":"2021031822394118000_B26","doi-asserted-by":"crossref","unstructured":"Lyddy,  F., Barnes-Holmes,  D., & Hampson,  P. J. (2001). A transfer of sequence function via equivalence in a connectionist network. Psychological Record, 51(3), 409\u2013428.","DOI":"10.1007\/BF03395406"},{"key":"2021031822394118000_B27","doi-asserted-by":"crossref","unstructured":"Mautner,  J., Makmal,  A., Manzano,  D., Tiersch,  M., & Briegel,  H. J. (2015). Projective simulation for classical learning agents: A comprehensive investigation. New Gener. Comput., 33(1), 69\u2013114.","DOI":"10.1007\/s00354-015-0102-0"},{"key":"2021031822394118000_B28","doi-asserted-by":"crossref","unstructured":"Mavroeidis,  D., & Bingham,  E. (2010). Enhancing the stability and efficiency of spectral ordering with partial supervision and feature selection. Knowledge and Information Systems, 23(2), 243\u2013265.","DOI":"10.1007\/s10115-009-0215-1"},{"key":"2021031822394118000_B29","doi-asserted-by":"crossref","unstructured":"McClelland,  J. L.\n           (2009). The place of modeling in cognitive science. Topics in Cognitive Science, 1(1), 11\u201338.","DOI":"10.1111\/j.1756-8765.2008.01003.x"},{"key":"2021031822394118000_B30","doi-asserted-by":"crossref","unstructured":"McClelland,  J. L.\n           (2013). Integrating probabilistic models of perception and interactive neural networks: A historical and tutorial review. Frontiers in Psychology, 4, 503.","DOI":"10.3389\/fpsyg.2013.00503"},{"key":"2021031822394118000_B31","doi-asserted-by":"crossref","unstructured":"Melnikov,  A. A., Makmal,  A., Dunjko,  V., & Briegel,  H. J. (2017). Projective simulation with generalization. Scientific Reports, 7(1), 14430.","DOI":"10.1038\/s41598-017-14740-y"},{"key":"2021031822394118000_B32","doi-asserted-by":"crossref","unstructured":"Mofrad,  A. A., Yazidi,  A., Hammer,  H. L., & Arntzen,  E. (2020). Equivalence projective simulation as a framework for modeling formation of stimulus equivalence classes. Neural Computation, 32(5), 912\u2013968.","DOI":"10.1162\/neco_a_01274"},{"key":"2021031822394118000_B33","doi-asserted-by":"crossref","unstructured":"Momennejad,  I.\n           (2020). Learning structures: Predictive representations, replay, and generalization. Current Opinion in Behavioral Sciences, 32, 155\u2013166.","DOI":"10.1016\/j.cobeha.2020.02.017"},{"key":"2021031822394118000_B34","unstructured":"Momennejad,  I., Otto,  A. R., Daw,  N. D., & Norman,  K. A. (2017). Offline replay supports planning: FMRI evidence from reward revaluation. bioRxiv:196758."},{"key":"2021031822394118000_B35","doi-asserted-by":"crossref","unstructured":"Momennejad,  I., Russek,  E. M., Cheong,  J. H., Botvinick,  M. M., Daw,  N. D., & Gershman,  S. J. (2017). The successor representation in human reinforcement learning. Nature Human Behaviour, 1(9), 680\u2013692.","DOI":"10.1038\/s41562-017-0180-8"},{"key":"2021031822394118000_B36","doi-asserted-by":"crossref","unstructured":"Ninness,  C., Ninness,  S. K., Rumph,  M., & Lawson,  D. (2018). The emergence of stimulus relations: Human and computer learning. Perspectives on Behavior Science, 41(1), 121\u2013154.","DOI":"10.1007\/s40614-017-0125-6"},{"key":"2021031822394118000_B37","unstructured":"O'Keefe,  J., & Nadel,  L. (1978). The hippocampus as a cognitive map. Oxford: Clarendon Press."},{"key":"2021031822394118000_B38","doi-asserted-by":"crossref","unstructured":"O'Mara,  H.\n           (1991). Quantitative and methodological aspects of stimulus equivalence. Journal of the Experimental Analysis of Behavior, 55(1), 125\u2013132.","DOI":"10.1901\/jeab.1991.55-125"},{"key":"2021031822394118000_B39","doi-asserted-by":"crossref","unstructured":"Parr,  T., Markovic,  D., Kiebel,  S. J., & Friston,  K. J. (2019). Neuronal message passing using mean-field, Bethe, and marginal approximations. Scientific Reports, 9(1), 1\u201318.","DOI":"10.1038\/s41598-018-38246-3"},{"key":"2021031822394118000_B40","doi-asserted-by":"crossref","unstructured":"Ratcliff,  R., Smith,  P. L., Brown,  S. D., & McKoon,  G. (2016). Diffusion decision model: Current issues and history. Trends in Cognitive Sciences, 20(4), 260\u2013281.","DOI":"10.1016\/j.tics.2016.01.007"},{"key":"2021031822394118000_B41","unstructured":"Ried,  K., Eva,  B., M\u00fcller,  T., & Briegel,  H. J. (2019). How a minimal learning agent can infer the existence of unobserved variables in a complex environment. arXiv:1910.06985."},{"key":"2021031822394118000_B42","doi-asserted-by":"crossref","unstructured":"Russek,  E. M., Momennejad,  I., Botvinick,  M. M., Gershman,  S. J., & Daw,  N. D. (2017). Predictive representations can link model-based reinforcement learning to model-free mechanisms. PLOS Computational Biology, 13(9), e1005768.","DOI":"10.1371\/journal.pcbi.1005768"},{"key":"2021031822394118000_B43","doi-asserted-by":"crossref","unstructured":"Schw\u00f6bel,  S., Kiebel,  S., & Markovi\u0107,  D. (2018). Active inference, belief propagation, and the Bethe approximation. Neural Computation, 30(9), 2530\u20132567.","DOI":"10.1162\/neco_a_01108"},{"key":"2021031822394118000_B44","unstructured":"Shrager,  J., Hogg,  T., & Huberman,  B. A. (1987). Observation of phase transitions in spreading activation networks. Science, 236(4805), 1092\u20131094."},{"key":"2021031822394118000_B45","doi-asserted-by":"crossref","unstructured":"Sidman,  M.\n           (1971). Reading and auditory-visual equivalences. Journal of Speech, Language, and Hearing Research, 14(1), 5\u201313.","DOI":"10.1044\/jshr.1401.05"},{"key":"2021031822394118000_B46","unstructured":"Sidman,  M.\n           (1990). Equivalence relations: Where do they come from? In D. E.Blackman & H.Lejeune (Eds.), Behaviour analysis in theory and practice: Contributions and controversies (pp. 93\u2013114). Mahwah, NJ: Erlbaum."},{"key":"2021031822394118000_B47","unstructured":"Sidman,  M.\n           (1994). Equivalence relations and behavior: A research story. Authors Cooperative."},{"key":"2021031822394118000_B48","doi-asserted-by":"crossref","unstructured":"Sidman,  M., Cresson Jr.,  O., & Willson-Morris,  M. (1974). Acquisition of matching to sample via mediated transfer 1. Journal of the Experimental Analysis of Behavior, 22(2), 261\u2013273.","DOI":"10.1901\/jeab.1974.22-261"},{"key":"2021031822394118000_B49","doi-asserted-by":"crossref","unstructured":"Sidman,  M., Rauzin,  R., Lazar,  R., Cunningham,  S., Tailby,  W., & Carrigan,  P. (1982). A search for symmetry in the conditional discriminations of rhesus monkeys, baboons, and children. Journal of the Experimental Analysis of Behavior, 37(1), 23\u201344.","DOI":"10.1901\/jeab.1982.37-23"},{"key":"2021031822394118000_B50","unstructured":"Sidman,  M., & Tailby,  W. (1982). Conditional discrimination vs. matching to sample: An expansion of the testing paradigm. Journal of the Experimental Analysis of Behavior, 37(1), 5\u201322."},{"key":"2021031822394118000_B51","doi-asserted-by":"crossref","unstructured":"Sidman,  M., Willson-Morris,  M., & Kirk,  B. (1986). Matching-to-sample procedures and the development of equivalence relations: The role of naming. Analysis and intervention in Developmental Disabilities, 6(1\u20132), 1\u201319.","DOI":"10.1016\/0270-4684(86)90003-0"},{"key":"2021031822394118000_B52","doi-asserted-by":"crossref","unstructured":"Spencer,  T. J., & Chase,  P. N. (1996). Speed analyses of stimulus equivalence. Journal of the Experimental Analysis of Behavior, 65(3), 643\u2013659.","DOI":"10.1901\/jeab.1996.65-643"},{"key":"2021031822394118000_B53","doi-asserted-by":"crossref","unstructured":"Stachenfeld,  K. L., Botvinick,  M. M., & Gershman,  S. J. (2017). The hippocampus as a predictive map. Nature Neuroscience, 20(11), 1643.","DOI":"10.1038\/nn.4650"},{"key":"2021031822394118000_B54","doi-asserted-by":"crossref","unstructured":"Steingrimsdottir,  H. S., & Arntzen,  E. (2011). Using conditional discrimination procedures to study remembering in an Alzheimer's patient. Behavioral Interventions, 26(3), 179\u2013192.","DOI":"10.1002\/bin.334"},{"key":"2021031822394118000_B55","doi-asserted-by":"crossref","unstructured":"Stella,  F., Baracskay,  P., O'Neill,  J., & Csicsvari,  J. (2019). Hippocampal reactivation of random trajectories resembling Brownian diffusion. Neuron, 102(2), 450\u2013461.","DOI":"10.1016\/j.neuron.2019.01.052"},{"key":"2021031822394118000_B56","unstructured":"Sutton,  R. S., & Barto,  A. G. (2018). Reinforcement learning: An introduction. Cambridge, MA: MIT Press."},{"key":"2021031822394118000_B57","unstructured":"Sutton,  R. S., Szepesv\u00e1ri,  C., Geramifard,  A., & Bowling,  M. (2008). Dyna-style planning with linear function approximation and prioritized sweeping. In Proceedings of the Twenty-Fourth Conference on Uncertainty in Artificial Intelligence (pp. 528\u2013536). Arlington, VA: AUAI Press."},{"key":"2021031822394118000_B58","doi-asserted-by":"crossref","unstructured":"Tolman,  E. C.\n           (1948). Cognitive maps in rats and men. Psychological Review, 55(4), 189\u2013208.","DOI":"10.1037\/h0061626"},{"key":"2021031822394118000_B59","doi-asserted-by":"crossref","unstructured":"Tovar,  \u00c1. E., & Westermann,  G. (2017). A neurocomputational approach to trained and transitive relations in equivalence classes. Frontiers in Psychology, 8, 1848.","DOI":"10.3389\/fpsyg.2017.01848"},{"key":"2021031822394118000_B60","doi-asserted-by":"crossref","unstructured":"Wang,  B., Pourshafeie,  A., Zitnik,  M., Zhu,  J., Bustamante,  C. D., Batzoglou,  S., & Leskovec,  J. (2018). Network enhancement as a general method to denoise weighted biological networks. Nature Communications, 9(1), 3108.","DOI":"10.1038\/s41467-018-05469-x"},{"key":"2021031822394118000_B61","unstructured":"Wimmer,  G. E., & Shohamy,  D. (2012). Preference by association: How memory mechanisms in the hippocampus bias decisions. Science, 338(6104), 270\u2013273."}],"container-title":["Neural Computation"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/direct.mit.edu\/neco\/article-pdf\/33\/2\/483\/1896861\/neco_a_01346.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"http:\/\/direct.mit.edu\/neco\/article-pdf\/33\/2\/483\/1896861\/neco_a_01346.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2021,3,18]],"date-time":"2021-03-18T22:41:13Z","timestamp":1616107273000},"score":1,"resource":{"primary":{"URL":"https:\/\/direct.mit.edu\/neco\/article\/33\/2\/483\/95644\/Enhanced-Equivalence-Projective-Simulation-A"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,2,1]]},"references-count":61,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2021,2,1]]},"published-print":{"date-parts":[[2021,2,1]]}},"URL":"https:\/\/doi.org\/10.1162\/neco_a_01346","relation":{},"ISSN":["0899-7667","1530-888X"],"issn-type":[{"value":"0899-7667","type":"print"},{"value":"1530-888X","type":"electronic"}],"subject":[],"published-other":{"date-parts":[[2021,2]]},"published":{"date-parts":[[2021,2,1]]}}}