title: Algebraic properties of If-Then-Else and commutative three-valued tests

authors: Soo, Khi-Ui

abstract: This paper establishes a finite axiomatization of possibly non-halting computer programs and tests, with the if-then-else operation. The model is a two-sorted algebra, with one sort being the programs and the other being the tests. The main operation on programs is composition, and 1 and 0 represent the programs skip and loop (i.e. never halts) respectively. Programs are modeled as partial functions on some state space X, with tests modeled as partial predicates on X. The operations on the tests are the usual logical connectives T and F. In addition, there is the hybrid operation of if-then-else, and the test-valued operation H on programs which is true when a program halts, and undefined otherwise. The halting operation H implies that operations of domain D and domain join may also be expressed. When tests are assumed to be possibly non-halting, the evaluation strategy of the logical connectives affects the result. Here we model parallel evaluation, as opposed to the common sequential (or short-circuit) evaluation strategy. For example, we view α β as false if either α or β is false, even if the other does not halt.

text: Algebraic properties of If-Then-Else and commutative three-valued tests This paper establishes a finite axiomatization of possibly non-halting computer programs and tests, with the if-then-else operation. The model is a two-sorted algebra, with one sort being the programs and the other being the tests. The main operation on programs is composition, and 1 and 0 represent the programs skip and loop (i.e. never halts) respectively. Programs are modeled as partial functions on some state space X, with tests modeled as partial predicates on X. The operations on the tests are the usual logical connectives T and F. In addition, there is the hybrid operation of if-then-else, and the test-valued operation H on programs which is true when a program halts, and undefined otherwise. The halting operation H implies that operations of domain D and domain join may also be expressed. When tests are assumed to be possibly non-halting, the evaluation strategy of the logical connectives affects the result. Here we model parallel evaluation, as opposed to the common sequential (or short-circuit) evaluation strategy. For example, we view α β as false if either α or β is false, even if the other does not halt.

year: 2019

title: Managed Aquifer Recharge in the Poverty Bay Flats

authors: Hampton, G. W.

abstract: In 2012 a report was commissioned by the Gisborne District Council (GDC) to examine groundwater resources in the Poverty Bay flats. This report found that groundwater elevations within the Makauri Gravel aquifer (the aquifer subject to the greatest groundwater abstractions), were declining at statistically significant rates, probably due to groundwater abstractions (White et al., 2012). As a result, the GDC is investigating whether managed aquifer recharge (MAR) can be used to help achieve the sustainable management of groundwater resources within the Poverty Bay flats. MAR is “the purposeful recharge of water to aquifers for subsequent recovery or environmental benefit” (Dillon et al., 2013, p. 2). Though MAR is uncommon in New Zealand, increasing pressures on groundwater may change this. GDC is investigating two different methods of MAR, well-injection (in conjunction with Golder Associates), and infiltration basins, which is the focus of this study.

text: Managed Aquifer Recharge in the Poverty Bay Flats In 2012 a report was commissioned by the Gisborne District Council (GDC) to examine groundwater resources in the Poverty Bay flats. This report found that groundwater elevations within the Makauri Gravel aquifer (the aquifer subject to the greatest groundwater abstractions), were declining at statistically significant rates, probably due to groundwater abstractions (White et al., 2012). As a result, the GDC is investigating whether managed aquifer recharge (MAR) can be used to help achieve the sustainable management of groundwater resources within the Poverty Bay flats. MAR is “the purposeful recharge of water to aquifers for subsequent recovery or environmental benefit” (Dillon et al., 2013, p. 2). Though MAR is uncommon in New Zealand, increasing pressures on groundwater may change this. GDC is investigating two different methods of MAR, well-injection (in conjunction with Golder Associates), and infiltration basins, which is the focus of this study.

year: 2015-11

title: Contextualizing Indigenous people and the state of exception: New Zealand's Waikeria Prison protest

authors: Martin, Jessica

abstract: On Tuesday, December 29, 2020, 16 protesters at Waikeria Prison, one of New Zealand's largest male prisons, engaged in a six-day standoff with prison guards to protest inhumane prison conditions. The Department of Corrections framed the event as an aimless riot, delegitimizing the intentional demonstration of resistance against state violence. Imprisoned intellectuals, specifically Imprisoned Black Radical tradition, have long examined and centered the prison as the harshest instrument of the state linked to the struggles of the collective. However, voices from imprisoned intellectuals are rarely considered in academic scholarship despite acute analysis of the state and liberation. This article employs the state of exception to contextualize the Waikeria protest. Particular attention is devoted to the ‘state of continuity,’ which allows for a broader understanding of a permanent state of racialized oppression and marginalization faced by Indigenous and Black communities in racialized-settler-colonial contexts. Populations designated as the exception are thus framed as a threat targeted for militaristic police intervention. This article concludes by extending the discussion of the state of continuity to include how expressions of rage and dissent by Indigenous and Black people are viewed as a direct threat to the sovereign order but are necessary for revolutionary change.

text: Contextualizing Indigenous people and the state of exception: New Zealand's Waikeria Prison protest On Tuesday, December 29, 2020, 16 protesters at Waikeria Prison, one of New Zealand's largest male prisons, engaged in a six-day standoff with prison guards to protest inhumane prison conditions. The Department of Corrections framed the event as an aimless riot, delegitimizing the intentional demonstration of resistance against state violence. Imprisoned intellectuals, specifically Imprisoned Black Radical tradition, have long examined and centered the prison as the harshest instrument of the state linked to the struggles of the collective. However, voices from imprisoned intellectuals are rarely considered in academic scholarship despite acute analysis of the state and liberation. This article employs the state of exception to contextualize the Waikeria protest. Particular attention is devoted to the ‘state of continuity,’ which allows for a broader understanding of a permanent state of racialized oppression and marginalization faced by Indigenous and Black communities in racialized-settler-colonial contexts. Populations designated as the exception are thus framed as a threat targeted for militaristic police intervention. This article concludes by extending the discussion of the state of continuity to include how expressions of rage and dissent by Indigenous and Black people are viewed as a direct threat to the sovereign order but are necessary for revolutionary change.

year: 2024-05-16