Complexity Theory Research Articles

A novel fractional neural grey system model with discrete q-derivative

The challenge of predicting time series with limited data has evolved over time due to nonlinearity, complexity, and limited information. It can be perceived as a mapping of dynamical systems in one-dimensional space. This article proposes a neural grey system to tackle this challenge. The system enhances its ability to fit nonlinearity by employing polynomials, captures complexity through a fractional-order cumulant operator, and resolves information-poor uncertainty by utilizing grey system modeling techniques. The model effectively integrates research findings from neural computing, uncertainty theory, and complexity theory at a theoretical level. It accurately describes dynamic processes of complex systems. Additionally, we have reduced the complexity of calculations in the algorithm design. We selected a dataset of total retail sales of consumer goods to test the model’s validity and applicability. Our experiments demonstrate that the newly proposed grey forecasting model can effectively forecast time series with small samples, offering good forecasting outcomes and generalization ability.

Book Review: Complexity theory for social work practice by Fiona McDermott, Kerry Brydon, Alex Haynes, and Felicity Moon

Book Review: <i>Complexity theory for social work practice</i> by Fiona McDermott, Kerry Brydon, Alex Haynes, and Felicity Moon

Travel Animosity and Affinity: A Chaordic Perspective

The aim of this study is to investigate the complex effects of animosity and affinity on travel intentions. In so doing, we draw from a sample of 400 Greek holidaymakers and use complexity theory to examine the chaordic influence of animosity and affinity on their intentions to potentially travel to Russia in the near future. Contrary to previous studies on animosity and affinity which adopted a linear analytic approach, we use fuzzy-set Qualitative Comparative Analysis (fsQCA) for the examination of the derived complex configurations. The results reveal three pathways that can influence travel intentions: (i) affinity and animosity, (ii) destination characteristics, and (iii) risk perceived animosity. Overall, the study adds to extant literature on travel decision-making at times of crisis as it examines animosity and affinity concurrently, revealing the complexity underpinning travel decisions. The study also enables destination planners to improve their crisis management and resilience plans.

Circular economy in tourism and hospitality: A micro-meso-macro framework for inter-disciplinary research

This contribution elaborates on the theoretical and practical implications of the circular economy in tourism and hospitality through an inter-disciplinary approach advancing novel possibilities for future research. Acknowledging the literature gap on circular economy in tourism and hospitality as an under-researched and under-theorised area of research, this contribution identifies a set of theoretical lenses that can help to elaborate the notion of circular economy and unpack it through an inter-disciplinary approach for future research. It does so by discussing the notion of circular economy through a micro-meso-macro framework combining practice theory, network theory, complexity theory, and the spatial and mobilities turn in social sciences. The originality of this work lies in its inter-disciplinary approach based on a micro-meso-macro theoretical framework offering novel opportunities to discuss, envision, and operationalize circular regenerative processes in tourism futures in terms of multidimensional, networked, complex, practice-based, and localised processes and operations.

Conducting sustainability research in the anthropocene: toward a relational approach

Scholars and practitioners are urgently highlighting the need to apply a relational approach to effectively address societal crises. At the same time, little is known about the associated challenges, and there is little advice regarding how to operationalize this approach in sustainability science. Against this background, this article explores how we can break out of our current paradigms and approaches, and instead apply relational thinking, being, and acting in the way we conduct research. To achieve this, we systematically list all major research phases, and assess possible pathways for integrating a relational paradigm for each step. We show that moving toward a relational paradigm requires us to methodically question and redefine existing theories of change, concepts, and approaches, for instance by combining abductive reasoning, first-person inquiries, and decentering the human through critical complexity theory. Challenging mainstream thought, and daring to ask different questions in each step is crucial to ultimately shift scientific norms and systems. Hence, we offer a catalog of questions that may help to systematically integrate relational being, thinking, and acting into the process, as a tool for transforming current paradigms in research, and associated education and practice. Finally, we highlight the importance of further research to develop and refine our outcomes.

Unveiling the impact of ChatGPT on travel consumer behaviour: exploring trust, attribute, and sustainable-tourism action

ABSTRACT This study examines the influence of ChatGPT on tourist behaviour using complexity theory. Factors such as media richness, anthropomorphism, trust in ChatGPT, and trust in online travel agencies are investigated to understand their effects on purchasing intentions and word-of-mouth, along with a moderator of sustainable-tourism action (practice). Results revealed the relationships among the variables, highlighting the crucial role of trust in shaping consumer behaviour. A comparison between high and low levels of sustainable-tourism practice groups provides further insights. The study discusses implications for the travel industry, emphasising the importance of leveraging ChatGPT to enhance tourist trust and sustainable actions.

Essentials of ‘the Great Reset’ through Complexity Matching

This qualitative study employs a thematic network analysis of the literature to explore the implications and evaluations of the ‘Great Reset’. Delving into how complexity theory, especially the principles related to complex systems and coordination, can be applied, this research aims to promote resilience and facilitate comprehensive systemic transformation. This study identifies critical ‘Great Reset’ components that align or conflict with stakeholders’ needs, objectives, and capabilities by examining how diverse stakeholders function within intricate and interconnected systems.

Evaluations of countering violent extremism programs: Linking success to content, approach, setting, and participants

Since the September 11 attacks, prevention and countering violent extremism (P/CVE) programs have rapidly increased worldwide, garnering significant interest among researchers. This paper is a systematic review focusing on the evaluations of primary, secondary and tertiary prevention programs from 2001 until 2020. The review identified 74 program evaluations that included satisfactory measures and metrics. Only 32% of the studies deemed the intervention successful, 55% described limited success, and 8% deemed the program had failed. Many of the programs evaluated failed to reach their objectives; some generated negative outcomes such as community disdain and an increase in the likelihood of alienation and stigma. Success was largely a self-assessed measure by the facilitators or stakeholders of the programs or the evaluators of the study. Success indicators can be operationalized as the degree of enhanced sense of belonging (connectedness to the community, social connection), trust and willingness to engage in programs, development of critical thinking skills (integrative complexity theory), and a strong sense of worth (quest for significance). Without a generally accepted set of metrics and no cohesive framework for conducting evaluations, this review offers an important addition to the field on the evidence suitable for program evaluations. An important aim of this systematic review was to identify what makes an effective and successful countering violent extremism program. The key findings indicate that enhancing belonging, identity, trust and community engagement, acknowledging perceptions of injustice, religious mentoring, and the promotion of critical thinking/self-reflection are associated with successful programs. The findings press upon policymakers, funders, and researchers the need to consider and support high-quality evaluations of programs.

Analysing the performance of a health innovation ecosystem in the COVID-19 crisis: complexity and chaos theory perspective

BackgroundThis research delves into the complexity management of collaborative networks and interorganizational systems in the health innovation ecosystem on the basis of a best practice in the coronavirus disease 2019 (COVID-19) crisis. The objective is to offer specific solutions and guidelines to stakeholders in the health innovation ecosystem to control the chaos resulting from unexpected events along the ecosystem development and evolution path.MethodsFor this purpose, the performance of the Health Innovation Ecosystem in Iran (the Every Home is a Health Base plan) has been examined through a detailed and in-depth analysis of events and actions taken using documents, reports and interviews with experts. The practical application of chaos and complex adaptive system features (adaptation, time horizons, edge of chaos, sensitivity to initial conditions, state space and strange attractors) is introduced to identify and manage the transition from a state where the health innovation ecosystem is on the edge of chaos and prone to failure. Data were collected through studying documents, reports and interviews with experts, and then analysed using qualitative content analysis techniques, open and axial coding and metaphors derived from complexity and chaos theories.ResultsThe findings indicate that to understand and embrace the complexity of the health innovation ecosystem throughout its development and evolution and manage and lead it through the edge of chaos towards successful interorganizational systems performance, it is necessary to use gap analysis to achieve consensus, establish a highly interactive governance structure with key stakeholders of the ecosystem, maintain flexibility to control bifurcations (butterfly effect), prevent transforming emergency solutions into standard routines and ensure the sustainability of the ecosystem against future threats by long-term financial security.ConclusionsThis research provides insights into the dynamics of complex health systems and offers strategies for promoting successful innovation through collaborative networks and interorganizational systems in the development and evolution of the health innovation ecosystem. By embracing complexity and chaos, healthcare professionals, policy-makers and researchers can collaboratively address complex challenges and improve outcomes in health network activities. The conclusion section provides guidelines for successfully managing the complexity of the ecosystem and offers suggestions for further research.

Science curriculum-making for the Anthropocene: perspectives and possibilities

ABSTRACT This paper illuminates how science curriculum-making can be reinvigorated to address urgent local and global socioscientific issues that centres place as an interconnected part of larger socio-ecological and socio-technical systems. Given how industrial and capitalistic extractive practices have pushed the planet beyond its complex life-sustaining limits, we draw on theoretical perspectives that recognise schools as complex systems, nested within local, regional, and global social-ecological-technological systems. Science curriculum-making in these systems prompts dialogue regarding knowledge and competencies required to address planetary sustainability, as well as ontological questions connected to systems, relations, and responsibility. Consequently, schools are important places for curriculum enactment practices. Furthermore, teachers, students, administrators, and school community members are enmeshed with local ecologies that are constituted in the cultural, material, and social arrangements found in or brought to a school and its local community. In our work, we draw on a curriculum commonplaces perspective to investigate curriculum-making practices. Specifically, we use empirical data from two cases of elementary and secondary science teachers developing and enacting curriculum and adopt a philosophical-empirical deductive approach illustrative of how to apply complexity theory, systems thinking, and associated ontological and epistemological views to practical reasoning of science curriculum-making for schools.

Negotiating Complexity within the Dialectical and Cosmopolitan Johannine Situation

While understandings of Johannine Christianity have been many and varied, single-issue analyses no longer suffice. Things were more complex than simply inferring that synagogue-Johannine tensions, pneumatizing Gnostics, heretical secessionists, or Petrine ecclesiasts was the lone issue. Nor is a two-level reading of the Johannine narrative plausible, as there is no evidence of alien material underlying John’s story of Jesus. Thus, the early, middle, and later phases of the Johannine tradition must be taken into consideration, as an autonomous memory of Jesus is best seen as developing in a first edition, which was finalized later by the Johannine Elder after writing the Epistles. Within that perspective, Social Identity Complexity Theory is well applied as a means of understanding a number of partners in dialogue within the Johannine Situation, including the stances of Jesus remembered by the Fourth Evangelist and Johannine Elder, who addressed no fewer than seven crises over seven decades within the cosmopolitan Johannine Situation.

Integrated System Responses for Families Impacted by Violence: A Scoping Review.

Violence within families is a complex problem which significantly impacts health and wellbeing. Despite the ubiquitous call for integrated family violence service delivery, integrated approaches vary significantly and challenges to implementation remain. This scoping review explored how integrated approaches to family violence service delivery are conceptualised within international and Aotearoa New Zealand literature. Following a documented scoping review process identified from literature, dynamic interplay between system agents within integrated family violence service delivery were mapped with the assistance of a complexity theory lens. We analysed characteristics of included studies, agents involved, how they interacted and the methods and mechanisms of integration among them. Seventy-two published reports were included. The most common interactions occurred between statutory agencies such as police and child protection. While health care service providers were included within 55 studies, their engagement was often peripheral. Qualitative analysis elucidated three broad pathways to service delivery impact underpinned by systems-centred, person-centred, or Indigenous-centred worldviews. Integrated approaches to family violence service delivery are highly variable. Despite a strong assumption that integration leads to improved safety, health, and wellbeing for care-seekers, most studies did not include evidence of such impact. Consideration of how worldviews characterise service provision provides insight into why integration has proven challenging over time.

Linking absorptive capacity to project success via mediating role of customer knowledge management capability: the role of environmental complexity

PurposeThe purpose of this study is to investigate the relationship between the absorptive capacity (AC) of a firm and project success (PS), with particular attention to the mediating role of customer knowledge management capability (CKMC) and the moderating role of environmental complexity (EC). By using data collected from Turkish SMEs across different sectors, the study seeks to understand how AC impacts project success, how CKMC mediates this relationship, and how EC moderates the link between AC and CKMC. The research contributes to both theory and practice by providing insights into these relationships and suggesting future research directions.Design/methodology/approachThis study focuses on Small and Medium-sized Enterprises (SMEs) in Turkey, specifically within the cities of Istanbul, Ankara, Izmir, and Konya. To gather data, the researchers utilized a non-probabilistic convenience sampling method and distributed self-administered surveys to a selected pool of 918 respondents including shift supervisors, project managers, and team members within these SMEs. The surveys were translated to Turkish to avoid language issues. Out of the surveys distributed, 401 valid responses were collected, resulting in a response rate of 43.68%.FindingsThe main findings of the study indicate that a firm’s absorptive capacity (AC) positively impacts project success and customer knowledge management capability (CKMC). Furthermore, CKMC plays a mediating role, positively influencing project success. Additionally, the study reveals the moderating effect of environmental complexity (EC) on the relationship between AC and CKMC, suggesting that as EC becomes more complex, it strengthens the link between AC and CKMC. Moreover, CKMC was found to mediate the moderating effect of EC on the relationship between AC and project success, emphasizing the significance of environmental complexity in this interaction.Research limitations/implicationsThis study’s limitations stem from its cross-sectional approach, which limits the ability to establish causal relationships between the constructs of absorptive capacity (AC), customer knowledge management capability (CKMC), and project success. It does not examine other potential mediators, such as customer relationship capability and innovation capability. Furthermore, the existing literature on this topic is scarce, suggesting a need for further research, particularly on constructs like team skills for managing CKMC. There is also an unexplored area around the effects of different forms of complexity, such as resource and technical complexity. Finally, further research is needed to understand how SMEs, which often face resource constraints, leverage AC in different functional domains for successful new product development.Practical implicationsThe study’s findings have significant practical implications for SMEs, highlighting the importance of absorptive capacity (AC) and customer knowledge management capability (CKMC) in promoting project success, particularly under conditions of environmental complexity. As businesses navigate uncertain environments, external knowledge acquisition becomes crucial for improvement and innovation. Efficient transformation of this knowledge can enhance project success rates. Thus, firms should cultivate a proactive, innovative, and risk-taking climate. Also, firms should regularly assess their AC and CKMC in the face of shifting stakeholder expectations and market competition. The ability to detect, integrate, and apply external knowledge in product and service development can significantly enhance project success rates.Originality/valueThis study’s originality lies in its exploration of the complex interplay between a firm’s absorptive capacity (AC), customer knowledge management capability (CKMC), environmental complexity (EC), and project success (PS). By examining Turkish SMEs across various sectors, the study uncovers the mediating role of CKMC and the moderating role of EC in the relationship between AC and PS. Furthermore, it reveals how the effect of AC on PS through CKMC strengthens with increasing environmental complexity. These findings offer fresh insights into the complexity theory and the factors influencing project success, providing a unique perspective for both academics and practitioners, with practical implications for managing SMEs in complex environments.

Technologies of the future agro-industrial complex in the aspect of complexity theory

The article is devoted to the problem area of the Russian agro-industrial complex – the complexity of the emerging set of technologies. The focus is on complexity theory, implemented within the framework of synergetics. The range of issues discussed are includes: prerequisites for the formation of complexity theory in agricultural science; creation of a generalized concept of the agricultural technologies complexity; architecture of the complexity of production, processing and food technologies as a whole; features of the mathematical apparatus for modeling agro-industrial complex technological complexes; an emergent effect that arises from the interaction of heterogeneous technologies that have a common goal; designing the complexity of connected technologies; the pace of the combined technologies development; technological requirements for the output parameters of processes throughout the entire technological chain; features of the design of complex technologies with a quantitative assessment of their level of complexity; consideration of a complex technological system as an object of synergetics. Particular attention was paid to the dialectical development of complexes of modern innovative technologies as the theoretical basis for the entry of the Russian agro-industrial complex into the Sixth technological order.

‘Atawhai’: a primary care provider-led response to family violence in Aotearoa New Zealand

BackgroundAs a key determinant of ill-health, family violence is inadequately responded to within Aotearoa New Zealand health policy and practice. Without adequate system support, health professionals can often be unsure of what to do, or how to help. Developed in response to this system gap, ‘Atawhai’ aims to make it easier for primary care professionals to respond to family violence.MethodsUnderpinned by indigenous Māori customs, Atawhai combines complexity theory and participatory research methodologies to be responsive to the complexity involved in family violence. We worked with 14 primary care professionals across ten whakawhitiwhiti kōrero wānanga (meetings for deliberate dialogue) to identify and develop primary care system pathways and tools for responding to family violence. This paper focuses on the development of Atawhai through wānanga and observation methods. Methods used to capture change will be reported separately.FindingsAtawhai is a relational response to family violence, focused on developing a network of trusted relationships between health and social care professionals to support safe responses to those accessing care. This study identified four key health system pathways to responsiveness and developed associated tools to support health care responsiveness to family violence. We found the quality of relationships, both among professionals and with those accessing care, coupled with critical reflection on the systems and structures that shape policy and practice are essential in generating change within primary care settings.ConclusionsAtawhai is a unique health care response to family violence evidenced on empirical knowledge of primary care professionals. Our theoretical lens calls attention to parts of the system often obscured by current health care responses to family violence. Atawhai presents an opportunity to develop a grassroots-informed, long-term response to family violence that evolves in response to needs.

Consumers' adoption intention to Metaverse applications: An exploration through fsQCA approach

AbstractMetaverse is an emergent technology that facilitates consumer interaction and participation in various activities within an integrated virtual environment. Considering the Metaverse's swift growth, comprehension of the perspectives and inclinations of its prospective users is critical. Considering configuration and complexity theories, this article examines the causal patterns of factors and fragmented perspectives concerning using Metaverse applications (M‐apps). It does so by examining how functional (ease of use, privacy), social (interactivity, presence), and personality (locus of control, openness to experience) factors combine as causal configurations to describe consumer adoption (MTA). Hence, fuzzy‐set qualitative comparative analysis is employed to empirically examine the proposed configurational model by analyzing a sample of 372 Chinese consumers of different M‐Apps. The notable MTA was determined to be explained under four distinct solutions with varying configurations of function, social, and personality in various combinations. The findings of this paper's complexity analysis constitute a scholarly and practical contribution to consumer acceptance of M‐apps, allowing for the customization of Metaverse functionality to meet every consumer's needs.

The impact of gamification on training, work engagement, and job satisfaction in banking

AbstractThis study contributes to the comparative analysis of outcomes between gamified and traditional training systems in the banking sector. On‐the‐job training is a vital aspect of the process of enhancing work performance within organizations. Thus, by employing a case‐based asymmetric configural approach rooted in nonlinear and contrarian case analysis, this research investigates the impact of gamified training on human resource development. A global empirical survey of 388 banking employees revealed that a combination of complexity theory and configural analysis provides valuable insights into the outcomes of both gamified and conventional training methods. In the face of increasing competition, banks are compelled to enhance their professionalism by boosting employee motivation. It becomes apparent that there is no straightforward, necessary and sufficient path available to guarantee high levels of engagement and job satisfaction. Notably, some of these results challenge the expectations of self‐determination theory (SDT), which posits the satisfaction of three basic psychological needs during training. These findings contribute to an enriched understanding of the nuanced application of complexity theory in the context of SDT research, particularly regarding the training and development of gamified systems for banking organizations and other service‐oriented sectors that can benefit from such innovative training approaches.

Toward A (Not The) Political Philosophy Of Populism: Democracy, Moral Dualism And Minimalst Theory In Christopher Lasch

Abstract I compare Christopher Lasch's thought to specific features that research in political science attributes to contemporary populism. Lasch openly favoured a historical form of populism but is rarely considered when current forms of populism are discussed. The research literature characterizes populism as superficially tied to democracy while undermining it, as committed to the moral binary of people and elites, and as intellectually “thin” because it does not engage with the complex theories that ground other ideologies. These characters make populism incoherent and inimical to democracy. Lasch manifests all three characters while connecting them to a sustained worldview. Humans’ awareness of death is the core feature that makes them rational, ethical and equal. Attempts to dilute that awareness are inimical to the equality at democracy's basis. Experts and professionals encourage this dilution by promising remedies and progress. Democracy depends on ordinary people who resist elites and their complex phraseologies.

Some New Results on Domination and Independent Dominating Set of Some Graphs

One area of graph theory that has been studied in great detail is dominance in graphs. Applications for dominating sets are numerous. In wireless networking, dominant sets are used to find effective paths inside ad hoc mobile networks. They have also been used in the creation of document summaries and safe electrical grid systems. A set &amp;lt;I&amp;gt;S&amp;lt;/I&amp;gt;⊆&amp;lt;I&amp;gt;V&amp;lt;/I&amp;gt; is said to be dominating set of &amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt; if for every &amp;lt;i&amp;gt;v &amp;lt;/i&amp;gt;є &amp;lt;I&amp;gt;V&amp;lt;/I&amp;gt;-&amp;lt;I&amp;gt;S&amp;lt;/I&amp;gt; there exists a vertex &amp;lt;i&amp;gt;u&amp;lt;/i&amp;gt; є &amp;lt;I&amp;gt;S&amp;lt;/I&amp;gt; such that &amp;lt;i&amp;gt;uv&amp;lt;/i&amp;gt; є &amp;lt;I&amp;gt;E&amp;lt;/I&amp;gt;. The dominance number of &amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt;, represented by &amp;lt;i&amp;gt;γ&amp;lt;/i&amp;gt;(&amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt;), is the lowest cardinality of vertices among the dominating set of &amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt;. A classic NP-complete decision problem in computational complexity theory determines whether, given a graph &amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt; and input &amp;lt;I&amp;gt;K&amp;lt;/I&amp;gt;, &amp;lt;i&amp;gt;γ&amp;lt;/i&amp;gt;(&amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt;) ≤ &amp;lt;I&amp;gt;K&amp;lt;/I&amp;gt;. This is known as the dominating set issue. Consequently, it is thought that calculating &amp;lt;i&amp;gt;γ&amp;lt;/i&amp;gt;(&amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt;) for each given graph &amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt; may not be possible to do with a feasible algorithm. In addition to efficient approximation tactics, there exist efficient exact techniques for various graph classes. If there are no neighboring vertices in a subset &amp;lt;I&amp;gt;S&amp;lt;/I&amp;gt;, then &amp;lt;I&amp;gt;S&amp;lt;/I&amp;gt;⊆&amp;lt;I&amp;gt;V&amp;lt;/I&amp;gt; is an independent set. Additionally, the empty set and the subset with just one vertex are independent. An independent dominating set of &amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt; is a set &amp;lt;I&amp;gt;S&amp;lt;/I&amp;gt; of vertices in a graph &amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt; that is both an independent and a dominating set of &amp;lt;I&amp;gt;G&amp;lt;/I&amp;gt;. This paper&amp;apos;s primary goal is to investigate the dominance and independent dominating set of many graphs, including the line graph, the alternate triangular belt graph, the bistar graph, the triangular snake graph, and others.

Counting Answers to Unions of Conjunctive Queries: Natural Tractability Criteria and Meta-Complexity

We study the problem of counting answers to unions of conjunctive queries (UCQs) under structural restrictions on the input query. Concretely, given a class C of UCQs, the problem #UCQ (C) provides as input a UCQ Ψ ∈ C and a database D and the problem is to compute the number of answers of Ψ in D. Chen and Mengel [PODS'16] have shown that for any recursively enumerable class C, the problem #UCQ (C) is either fixed-parameter tractable or hard for one of the parameterised complexity classes W[1] or #W[1]. However, their tractability criterion is unwieldy in the sense that, given any concrete class C of UCQs, it is not easy to determine how hard it is to count answers to queries in C. Moreover, given a single specific UCQ Ψ, it is not easy to determine how hard it is to count answers to Ψ. In this work, we address the question of finding a natural tractability criterion: The combined conjunctive query of a UCQ Ψ=φ 1 ∨ ... ∨ φ l is the conjunctive query ^ Ψ = φ_1 ∧ ... ∧ φ l . We show that under natural closure properties of C, the problem #UCQ (C) is fixed-parameter tractable if and only if the combined conjunctive queries of UCQs in C, and their contracts, have bounded treewidth. A contract of a conjunctive query is an augmented structure, taking into account how the quantified variables are connected to the free variables --- if all variables are free, then a conjunctive query is equal to its contract; in this special case the criterion for fixed-parameter tractability of #UCQ (C) thus simplifies to the combined queries having bounded treewidth. Finally, we give evidence that a closure property on C is necessary for obtaining a natural tractability criterion: We show that even for a single UCQ Ψ, the meta problem of deciding whether #UCQ (Ψ) can be solved in time O(|D| d ) is NP-hard for any fixed d ≥ 1. Moreover, we prove that a known exponential-time algorithm for solving the meta problem is optimal under assumptions from fine-grained complexity theory. As a corollary of our reduction, we also establish that approximating the Weisfeiler-Leman-Dimension of a UCQ is NP-hard.