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: Historical museum samples reveal signals of selection and drift in response to changing insecticide use in an agricultural pest moth

authors: Parvizi, Elahe

subjects: cotton bollworm

abstract: In response to environmental and human-imposed selective pressures, agroecosystem pests frequently undergo rapid evolution, with some species having a remarkable capacity to rapidly develop pesticide resistance. Temporal sampling of genomic data can comprehensively capture such adaptive changes over time, for example, by elucidating allele frequency shifts in pesticide resistance loci in response to different pesticides. Here, we leveraged museum specimens spanning over a century of collections to generate temporal contrasts between pre- and post-insecticide populations of an agricultural pest moth, Helicoverpa armigera. We used targeted exon sequencing of 254 samples collected across Australia from the pre-1950s (prior to insecticide introduction) to the 1990s, encompassing decades of changing insecticide use. Our sequencing approach focused on genes that are known to be involved in insecticide resistance, environmental sensation, and stress tolerance. We found an overall lack of spatial and temporal population structure change across Australia. In some decades (e.g., 1960s and 1970s), we found a moderate reduction of genetic diversity, implying stochasticity in evolutionary trajectories due to genetic drift. Temporal genome scans showed extensive evidence of selection following insecticide use, although the majority of selected variants were low impact. Finally, alternating trajectories of allele frequency change were suggestive of potential antagonistic pleiotropy. Our results provide new insights into recent evolutionary responses in an agricultural pest and show how temporal contrasts using museum specimens can improve mechanistic understanding of rapid evolution.

text: Historical museum samples reveal signals of selection and drift in response to changing insecticide use in an agricultural pest moth In response to environmental and human-imposed selective pressures, agroecosystem pests frequently undergo rapid evolution, with some species having a remarkable capacity to rapidly develop pesticide resistance. Temporal sampling of genomic data can comprehensively capture such adaptive changes over time, for example, by elucidating allele frequency shifts in pesticide resistance loci in response to different pesticides. Here, we leveraged museum specimens spanning over a century of collections to generate temporal contrasts between pre- and post-insecticide populations of an agricultural pest moth, Helicoverpa armigera. We used targeted exon sequencing of 254 samples collected across Australia from the pre-1950s (prior to insecticide introduction) to the 1990s, encompassing decades of changing insecticide use. Our sequencing approach focused on genes that are known to be involved in insecticide resistance, environmental sensation, and stress tolerance. We found an overall lack of spatial and temporal population structure change across Australia. In some decades (e.g., 1960s and 1970s), we found a moderate reduction of genetic diversity, implying stochasticity in evolutionary trajectories due to genetic drift. Temporal genome scans showed extensive evidence of selection following insecticide use, although the majority of selected variants were low impact. Finally, alternating trajectories of allele frequency change were suggestive of potential antagonistic pleiotropy. Our results provide new insights into recent evolutionary responses in an agricultural pest and show how temporal contrasts using museum specimens can improve mechanistic understanding of rapid evolution.

year: 2024

title: Working at the interface: Indigenous students’ experience of undertaking doctoral studies in Aotearoa New Zealand

authors: McKinley, Elizabeth

subjects: Māori

abstract: Māori (indigenous)¹ doctoral students in Aotearoa New Zealand face challenges not usually experienced by other doctoral candidates. We draw on data from in-depth interviews with 38 Māori doctoral candidates and argue that because of the tensions between academic disciplinary knowledge frameworks and knowledge drawn from te ao Māori (the Māori world) indigenous students have additional cultural, academic, and personal demands placed on them while aiming to produce research theses that meet conventional standards of academic scholarship. Complex methodological and ethical issues also emerge in undertaking doctoral research projects situated at the interface of academy and indigenous communities. Moreover, Māori students experience various degrees of tension between their sometimes strong cultural identities and their emerging and, therefore, less certain identities as researchers and scholars.

text: Working at the interface: Indigenous students’ experience of undertaking doctoral studies in Aotearoa New Zealand Māori (indigenous)¹ doctoral students in Aotearoa New Zealand face challenges not usually experienced by other doctoral candidates. We draw on data from in-depth interviews with 38 Māori doctoral candidates and argue that because of the tensions between academic disciplinary knowledge frameworks and knowledge drawn from te ao Māori (the Māori world) indigenous students have additional cultural, academic, and personal demands placed on them while aiming to produce research theses that meet conventional standards of academic scholarship. Complex methodological and ethical issues also emerge in undertaking doctoral research projects situated at the interface of academy and indigenous communities. Moreover, Māori students experience various degrees of tension between their sometimes strong cultural identities and their emerging and, therefore, less certain identities as researchers and scholars.

year: 2011