title: Generic tools via general refinement

authors: Reeves, Steve

subjects: basis for tools

abstract: Tools have become essential in the formal model-driven development of software but are very time consuming to build and often restricted to a particular semantic interpretation of a particular syntax. This is regrettable since there is large amount in common between tools, even if they do “implement” different syntaxes and different semantics.
We propose splitting tools into front- and back-ends where an operational semantics acts as the link between the two. We will not have much to say about the front-end and the link in this paper since it is theoretically straightforward. Instead, we concentrate on the second part and provide a well-motivated, general, mathematical framework to form the underlying theory that gives great flexibility to the back-end of a tool which is concerned with developing software via stepwise refinement.
From a general model of refinement between two entities, where the refinement is parameterised on contexts and observations, we build logical theories which have refinement as implication. Further, we consider what can be expected of a guarantee concerning the behaviour of an implementation relative to a specification. Then by fixing the contexts and observations in suitable ways, and so getting particular, special models of refinement, we give a formal interpretation of a guarantee. To this we add theory morphisms between special models, where a theory morphism can change the contexts and observations we can make in controlled and useful ways, mainly by preserving a refinement relation between entities even as we change them.
We show how the generality brought about by the parameterisation allows an example from the literature, which seems formally not to be a refinement, to be captured as a refinement, in accordance with our intuitions about the example.
In this way we show the flexibility of our theory for a refinement tool back-end. From this it follows that the effort put into building a tool based on our theory will be well-spent—a single tool should be parameterised (just as our theory is) to deal with the many different notions of refinement found in the literature. Thus we make a contribution to the problem of ensuring correctness and dependability of software using formal methods and tools of modelling, design, verification and validation.

text: Generic tools via general refinement Tools have become essential in the formal model-driven development of software but are very time consuming to build and often restricted to a particular semantic interpretation of a particular syntax. This is regrettable since there is large amount in common between tools, even if they do “implement” different syntaxes and different semantics.
We propose splitting tools into front- and back-ends where an operational semantics acts as the link between the two. We will not have much to say about the front-end and the link in this paper since it is theoretically straightforward. Instead, we concentrate on the second part and provide a well-motivated, general, mathematical framework to form the underlying theory that gives great flexibility to the back-end of a tool which is concerned with developing software via stepwise refinement.
From a general model of refinement between two entities, where the refinement is parameterised on contexts and observations, we build logical theories which have refinement as implication. Further, we consider what can be expected of a guarantee concerning the behaviour of an implementation relative to a specification. Then by fixing the contexts and observations in suitable ways, and so getting particular, special models of refinement, we give a formal interpretation of a guarantee. To this we add theory morphisms between special models, where a theory morphism can change the contexts and observations we can make in controlled and useful ways, mainly by preserving a refinement relation between entities even as we change them.
We show how the generality brought about by the parameterisation allows an example from the literature, which seems formally not to be a refinement, to be captured as a refinement, in accordance with our intuitions about the example.
In this way we show the flexibility of our theory for a refinement tool back-end. From this it follows that the effort put into building a tool based on our theory will be well-spent—a single tool should be parameterised (just as our theory is) to deal with the many different notions of refinement found in the literature. Thus we make a contribution to the problem of ensuring correctness and dependability of software using formal methods and tools of modelling, design, verification and validation.

year: 2008

title: Development of a Rhizosheath Selection Tool for screening perennial ryegrass (Lolium perenne L.) for reduced root competition against white clover (Trifolium repens L.) for soil phosphorus

authors: Yeates, Rebecca Maree

subjects: Agriculture

abstract: Perennial ryegrass (Lolium perenne L.) outcompetes white clover (Trifolium repens L.) for soil phosphorus [P], resulting in higher P fertiliser rates to overcome the competition. Perennial ryegrass has long, dense root hairs compared to white clover, which increase the root contact with soil (soil exploration) and root surface area for P uptake. This study was conducted to test whether the selection of perennial ryegrass with reduced root hair length and density would reduce root competition for P with no detrimental effect on the perennial ryegrass growth. 
A Rhizosheath Selection Tool [RST] was developed to select ryegrass populations with contrasting root hair length and density. The RST protocol used rhizosheath traits (the width and coverage of soil adhered to the extracted root system) along with the total seedling weight to select two distinct ryegrass populations. The low rhizosheath population had shorter, sparser root hairs on seminal roots and sparser root hairs on adventitious roots than the high rhizosheath population.
The two populations were then grown at five soil P levels in a glasshouse experiment and demonstrated that the rhizosheath trait selection had no detrimental effect on growth. There were no significant differences between the two population’s dry weight (g) and P concentration (mg P g-1 dry weight). However there was evidence to indicate that the high rhizosheath population was sometimes more efficient at P uptake with a larger total P content (mg P). 
The two perennial ryegrass populations were then grown with companion white clover in Olsen P 12 and 19 mg L⁻¹ soil with partitions separating the shoot systems to avoid shoot competition for light. The low rhizosheath population had reduced root competition with the companion white clover. In Olsen P 12 mg L⁻¹ soil, more P was partitioned to the white clover than the ryegrass, measured by total P content (mg P), and achieved a greater dry weight (g) than when grown with the HRS ryegrass. In Olsen P 19 mg L⁻¹ soil there was no rhizosheath selection effect on white clover growth, possibly because of the reduced need for soil exploration by roots under the higher soil P availability. 
The findings from this study confirmed that the RST for the selection of a perennial ryegrass population with a reduced capacity for root competition against white clover for soil P is effective. Furthermore, the RST selection had no detrimental effect to the ryegrass growth. This research highlights the importance of root traits in forage plant breeding, and the potential environmental and economic benefits a low rhizosheath perennial ryegrass could have in New Zealand’s pastoral farming system.

text: Development of a Rhizosheath Selection Tool for screening perennial ryegrass (Lolium perenne L.) for reduced root competition against white clover (Trifolium repens L.) for soil phosphorus Perennial ryegrass (Lolium perenne L.) outcompetes white clover (Trifolium repens L.) for soil phosphorus [P], resulting in higher P fertiliser rates to overcome the competition. Perennial ryegrass has long, dense root hairs compared to white clover, which increase the root contact with soil (soil exploration) and root surface area for P uptake. This study was conducted to test whether the selection of perennial ryegrass with reduced root hair length and density would reduce root competition for P with no detrimental effect on the perennial ryegrass growth. 
A Rhizosheath Selection Tool [RST] was developed to select ryegrass populations with contrasting root hair length and density. The RST protocol used rhizosheath traits (the width and coverage of soil adhered to the extracted root system) along with the total seedling weight to select two distinct ryegrass populations. The low rhizosheath population had shorter, sparser root hairs on seminal roots and sparser root hairs on adventitious roots than the high rhizosheath population.
The two populations were then grown at five soil P levels in a glasshouse experiment and demonstrated that the rhizosheath trait selection had no detrimental effect on growth. There were no significant differences between the two population’s dry weight (g) and P concentration (mg P g-1 dry weight). However there was evidence to indicate that the high rhizosheath population was sometimes more efficient at P uptake with a larger total P content (mg P). 
The two perennial ryegrass populations were then grown with companion white clover in Olsen P 12 and 19 mg L⁻¹ soil with partitions separating the shoot systems to avoid shoot competition for light. The low rhizosheath population had reduced root competition with the companion white clover. In Olsen P 12 mg L⁻¹ soil, more P was partitioned to the white clover than the ryegrass, measured by total P content (mg P), and achieved a greater dry weight (g) than when grown with the HRS ryegrass. In Olsen P 19 mg L⁻¹ soil there was no rhizosheath selection effect on white clover growth, possibly because of the reduced need for soil exploration by roots under the higher soil P availability. 
The findings from this study confirmed that the RST for the selection of a perennial ryegrass population with a reduced capacity for root competition against white clover for soil P is effective. Furthermore, the RST selection had no detrimental effect to the ryegrass growth. This research highlights the importance of root traits in forage plant breeding, and the potential environmental and economic benefits a low rhizosheath perennial ryegrass could have in New Zealand’s pastoral farming system.

year: 2018

title: He waipuna koropupū: Taranaki Māori wellbeing and suicide prevention

authors: Cameron, Ngaropi

abstract: The research project He Waipuna Koropupū aimed to explore and share a knowledge base that could inform practice in relation to Taranaki Māori suicide. The project was grounded upon the notion that through Taranaki knowledge and information we can make significant changes in our approach to life and to our whānau relationships. The project was primarily about whānau ora and the wellbeing of future generations; through the reclamation and sharing of Taranaki Māori knowledge that can support intergenerational change and transformation. Taranaki Māori whānau (extended family groupings), hapū (subtribal grouping) and iwi (tribal grouping) deserve access to Kaupapa Māori approaches in order to help reclaim and inform decision making processes.

text: He waipuna koropupū: Taranaki Māori wellbeing and suicide prevention The research project He Waipuna Koropupū aimed to explore and share a knowledge base that could inform practice in relation to Taranaki Māori suicide. The project was grounded upon the notion that through Taranaki knowledge and information we can make significant changes in our approach to life and to our whānau relationships. The project was primarily about whānau ora and the wellbeing of future generations; through the reclamation and sharing of Taranaki Māori knowledge that can support intergenerational change and transformation. Taranaki Māori whānau (extended family groupings), hapū (subtribal grouping) and iwi (tribal grouping) deserve access to Kaupapa Māori approaches in order to help reclaim and inform decision making processes.

year: 2017