title: Using Coq to Enforce the Checks-Effects-Interactions Pattern in DeepSEA Smart Contracts

authors: Britten, Daniel

subjects: software engineering

abstract: Using the DeepSEA system for smart contract proofs, this paper investigates how to use the Coq theorem prover to enforce that smart contracts follow the Checks-Effects-Interactions Pattern. This pattern is widely understood to mitigate the risks associated with reentrancy. The infamous "The DAO" exploit is an example of the risks of not following the Checks-Effects-Interactions Pattern. It resulted in the loss of over 50 million USD and involved reentrancy - the exploit used would not have been possible if the Checks-Effects-Interactions Pattern had been followed.
Remix IDE, for example, already has a tool to check that the Checks-Effects-Interactions Pattern has been followed as part of the Solidity Static Analysis module which is available as a plugin. However, aside from simply replicating the Remix IDE feature, implementing a Checks-Effects-Interactions Pattern checker in the proof assistant Coq also allows us to use the proofs, which are generated in the process, in other proofs related to the smart contract.
As an example of this, we will demonstrate an idea for how the modelling of Ether transfer can be simplified by using automatically generated proofs of the property that each smart contract function will call the Ether transfer method at most once (excluding any calls related to invoking other smart contracts). This property is a consequence of following a strict version of the Checks-Effects-Interactions Pattern as given in this paper.

text: Using Coq to Enforce the Checks-Effects-Interactions Pattern in DeepSEA Smart Contracts Using the DeepSEA system for smart contract proofs, this paper investigates how to use the Coq theorem prover to enforce that smart contracts follow the Checks-Effects-Interactions Pattern. This pattern is widely understood to mitigate the risks associated with reentrancy. The infamous "The DAO" exploit is an example of the risks of not following the Checks-Effects-Interactions Pattern. It resulted in the loss of over 50 million USD and involved reentrancy - the exploit used would not have been possible if the Checks-Effects-Interactions Pattern had been followed.
Remix IDE, for example, already has a tool to check that the Checks-Effects-Interactions Pattern has been followed as part of the Solidity Static Analysis module which is available as a plugin. However, aside from simply replicating the Remix IDE feature, implementing a Checks-Effects-Interactions Pattern checker in the proof assistant Coq also allows us to use the proofs, which are generated in the process, in other proofs related to the smart contract.
As an example of this, we will demonstrate an idea for how the modelling of Ether transfer can be simplified by using automatically generated proofs of the property that each smart contract function will call the Ether transfer method at most once (excluding any calls related to invoking other smart contracts). This property is a consequence of following a strict version of the Checks-Effects-Interactions Pattern as given in this paper.

year: 2021

title: The charm of time: Generational comparison, memorable tourism experiences, and quality of life in visits to a world heritage site, Kulangsu

authors: Li, Yanhan

abstract: In recent years, heritage tourism has seen a shift toward younger visitors, challenging the earlier view that it attracts primarily older visitors. How this emerging group of younger tourists differ from older tourists, and the reasons for such differences from a Chinese generational perspective, remain unclear. Whilst a significant literature exists on differences of personal histories the speed of technological change in China has been so rapid that many older people now use their smartphones for making payments, keeping in touch with extended family and for leisure pursuits, and one wonders if even recent past research has kept up with these changes of senior behaviour. Moreover, previous heritage research has focused mainly on pre-visit and on-site perceptions, with limited attention to post-visit outcomes, such as memorable tourism experiences (MTEs) and quality of life (QoL), and little consideration of the temporal changes in these variables. MTEs look at tourists’ experiences that could be recalled or remembered after tourism activities occurred (Kim et al., 2012). Subjective QoL refers to how individuals perceive or evaluate their own lives (Woo et al., 2016). Therefore, this study aims to examine generational differences in heritage tourism experiences and outcomes among Chinese tourists, with particular attention to the temporal dynamics of MTEs and QoL.
To address these gaps, this study adopted a mixed-methods approach. In the qualitative phase, three rounds of interviews with 65 participants compared pre-visit, on-site, and post-visit perceptions between Chinese Generation Zs and the Lost Generation regarding visits to Kulangsu, a World Heritage Site. Interview data suggested that both MTEs and QoL improvements changed within seven to fifteen days after the visit. In the quantitative phase, a closed-ended questionnaire validated generational differences identified qualitatively. In brief, the three-stage interview approach not only minimized post hoc rationalization but also facilitated the exploration of time intervals’ influence on MTEs and QoL. The Jaccard index was further applied to support a reasonable transition from qualitative findings and the correlation hypotheses development to the quantitative significance test. This design enabled the study to capture temporal dynamics of tourism experiences that are often overlooked in cross-sectional tourism research.
The quantitative phase then within a broader and more representative sample (889 respondents, including a middle-aged group), tested relationships among pre-visit, on-site, and post-visit perceptions, as well as the effects of time variables on MTEs and QoL. The unique mixed methods design effectively addressed the research questions and offers new directions for future tourism studies. 
This study also makes multiple contributions in terms of theoretical extension and application. First, it provides a generationally informed account of why, how, and for what purposes younger and older Chinese heritage tourists visit Kulangsu, showing the profound influence of generational background and presenting a coherent narrative of the two cohorts’ heritage visitations. Second, it offers an in-depth discussion of MTEs and QoL in the heritage tourism context, which were linked with pre-and during visit perception variables, confirming that heritage experiences must first be memorable in order to affect QoL. Third, it demonstrates that the time interval after a visit directly leads to a decline in the memorability of heritage experiences, which in turn results in a reduction of QoL improvements gained from the trip. This finding helps explain the decline in tourists’ temporal wellbeing improvement reported in previous studies. 
In addition, the results also have practical implications for heritage site management, particularly for Kulangsu, and highlight the need for other heritage destinations to tailor services to generational characteristics, especially for the emerging younger market, while focusing on visitor-cantered outcomes such as memorable experiences that can enhance people’s quality of life, even if for only a short period of time. The temporal elements of such enhancements of life quality are also discussed in the thesis.

text: The charm of time: Generational comparison, memorable tourism experiences, and quality of life in visits to a world heritage site, Kulangsu In recent years, heritage tourism has seen a shift toward younger visitors, challenging the earlier view that it attracts primarily older visitors. How this emerging group of younger tourists differ from older tourists, and the reasons for such differences from a Chinese generational perspective, remain unclear. Whilst a significant literature exists on differences of personal histories the speed of technological change in China has been so rapid that many older people now use their smartphones for making payments, keeping in touch with extended family and for leisure pursuits, and one wonders if even recent past research has kept up with these changes of senior behaviour. Moreover, previous heritage research has focused mainly on pre-visit and on-site perceptions, with limited attention to post-visit outcomes, such as memorable tourism experiences (MTEs) and quality of life (QoL), and little consideration of the temporal changes in these variables. MTEs look at tourists’ experiences that could be recalled or remembered after tourism activities occurred (Kim et al., 2012). Subjective QoL refers to how individuals perceive or evaluate their own lives (Woo et al., 2016). Therefore, this study aims to examine generational differences in heritage tourism experiences and outcomes among Chinese tourists, with particular attention to the temporal dynamics of MTEs and QoL.
To address these gaps, this study adopted a mixed-methods approach. In the qualitative phase, three rounds of interviews with 65 participants compared pre-visit, on-site, and post-visit perceptions between Chinese Generation Zs and the Lost Generation regarding visits to Kulangsu, a World Heritage Site. Interview data suggested that both MTEs and QoL improvements changed within seven to fifteen days after the visit. In the quantitative phase, a closed-ended questionnaire validated generational differences identified qualitatively. In brief, the three-stage interview approach not only minimized post hoc rationalization but also facilitated the exploration of time intervals’ influence on MTEs and QoL. The Jaccard index was further applied to support a reasonable transition from qualitative findings and the correlation hypotheses development to the quantitative significance test. This design enabled the study to capture temporal dynamics of tourism experiences that are often overlooked in cross-sectional tourism research.
The quantitative phase then within a broader and more representative sample (889 respondents, including a middle-aged group), tested relationships among pre-visit, on-site, and post-visit perceptions, as well as the effects of time variables on MTEs and QoL. The unique mixed methods design effectively addressed the research questions and offers new directions for future tourism studies. 
This study also makes multiple contributions in terms of theoretical extension and application. First, it provides a generationally informed account of why, how, and for what purposes younger and older Chinese heritage tourists visit Kulangsu, showing the profound influence of generational background and presenting a coherent narrative of the two cohorts’ heritage visitations. Second, it offers an in-depth discussion of MTEs and QoL in the heritage tourism context, which were linked with pre-and during visit perception variables, confirming that heritage experiences must first be memorable in order to affect QoL. Third, it demonstrates that the time interval after a visit directly leads to a decline in the memorability of heritage experiences, which in turn results in a reduction of QoL improvements gained from the trip. This finding helps explain the decline in tourists’ temporal wellbeing improvement reported in previous studies. 
In addition, the results also have practical implications for heritage site management, particularly for Kulangsu, and highlight the need for other heritage destinations to tailor services to generational characteristics, especially for the emerging younger market, while focusing on visitor-cantered outcomes such as memorable experiences that can enhance people’s quality of life, even if for only a short period of time. The temporal elements of such enhancements of life quality are also discussed in the thesis.

year: 2025

title: Keynote address: Dr. Catherine Love

authors: Love, Catherine

subjects: Maori

abstract: This keynote address for the National Māori Graduates of Psychology Symposium 2002 addresses the history and current state of psychology in New Zealand, with particular attention to issues affecting Maori.

text: Keynote address: Dr. Catherine Love This keynote address for the National Māori Graduates of Psychology Symposium 2002 addresses the history and current state of psychology in New Zealand, with particular attention to issues affecting Maori.

year: 2003