title: Investigating the memory requirements for publish/subscribe filtering algorithms

authors: Bittner, Sven

subjects: computer science

abstract: Various filtering algorithms for publish/subscribe systems have been proposed. One distinguishing characteristic is their internal representation of Boolean subscriptions: They either require conversions to disjunctive normal forms (canonical approaches) or are directly exploited in event filtering (non-canonical approaches).
In this paper, we present a detailed analysis and comparison of the memory requirements of canonical and non-canonical filtering algorithms. This includes a theoretical analysis of space usages as well as a verification of our theoretical results by an evaluation of a practical implementation. This practical analysis also considers time (filter) efficiency, which is the other important quality measure of filtering algorithms. By correlating the results of space and time efficiency, we conclude when to use non-canonical and canonical approaches.

text: Investigating the memory requirements for publish/subscribe filtering algorithms Various filtering algorithms for publish/subscribe systems have been proposed. One distinguishing characteristic is their internal representation of Boolean subscriptions: They either require conversions to disjunctive normal forms (canonical approaches) or are directly exploited in event filtering (non-canonical approaches).
In this paper, we present a detailed analysis and comparison of the memory requirements of canonical and non-canonical filtering algorithms. This includes a theoretical analysis of space usages as well as a verification of our theoretical results by an evaluation of a practical implementation. This practical analysis also considers time (filter) efficiency, which is the other important quality measure of filtering algorithms. By correlating the results of space and time efficiency, we conclude when to use non-canonical and canonical approaches.

year: 2005-01-01

title: Preteens’ concepts and development of privacy, and the relationship to decisions and actions undertaken in online social environments and with digital devices.

authors: Webster, Angela

subjects: preteens

abstract: A concern for privacy, the development of this, and how it becomes interpreted in offline and complex online environments has potential implications on young people’s wellbeing and safety.  Media often bring to attention more negative aspects of young people’s privacy in relation to their online pursuits, which raises questions about perceived risks to one’s privacy and actual risks encountered online and any subsequent implications.  This study looks at preteens’ broad concepts and development of privacy, and any relationship(s) these may have on their use of digital technologies and decisions and actions in online social contexts.  A review of literature related to preteens’ involvement in online social networks and issues of privacy presents a growing body of information, however, a scarcity of literature related to preteens’ concern for privacy, and the development of privacy concern, suggests this study offers new insights in this particular area.

Students (N=60) aged between 11 and under 13 years from three provincial New Zealand schools participated in this qualitative study, and key data were gathered through a survey.  Preteens indicated they valued privacy and specified its importance across dimensions of self.  Furthermore, a desire for autonomy and control in managing aspects of privacy in their offline and online worlds was evident.  However, concerns were raised regarding preteens’ perceived capabilities and their actual competencies and knowledge of the technical, social, and ethical complexities presented online and in the use of devices.  Also evident were inconsistencies in the types of support needed to care for the safety and wellbeing of young people.  This suggests young people continue to need regular and robust support from agencies they themselves identified as important, and included caregivers, schools, and peers. 

Opportunities to further develop caregivers’ skills and knowledge is recommended, so they may better understand the crucial role they have in supporting the safety and wellbeing of their child in their exploration of complex digital environments.  Their role is essential in positively contributing to the development of a concern for privacy.  Recommendations are made, for schools, educators, and education policy makers in their role in this development.  These include sustained teaching and learning opportunities across all learning levels in building related skills and competencies.  Sourcing perspectives from preteens themselves as the experts of their ideas, experiences and knowledge, is integral to understanding how they navigate privacy issues when living lives both offline and online.

text: Preteens’ concepts and development of privacy, and the relationship to decisions and actions undertaken in online social environments and with digital devices. A concern for privacy, the development of this, and how it becomes interpreted in offline and complex online environments has potential implications on young people’s wellbeing and safety.  Media often bring to attention more negative aspects of young people’s privacy in relation to their online pursuits, which raises questions about perceived risks to one’s privacy and actual risks encountered online and any subsequent implications.  This study looks at preteens’ broad concepts and development of privacy, and any relationship(s) these may have on their use of digital technologies and decisions and actions in online social contexts.  A review of literature related to preteens’ involvement in online social networks and issues of privacy presents a growing body of information, however, a scarcity of literature related to preteens’ concern for privacy, and the development of privacy concern, suggests this study offers new insights in this particular area.

Students (N=60) aged between 11 and under 13 years from three provincial New Zealand schools participated in this qualitative study, and key data were gathered through a survey.  Preteens indicated they valued privacy and specified its importance across dimensions of self.  Furthermore, a desire for autonomy and control in managing aspects of privacy in their offline and online worlds was evident.  However, concerns were raised regarding preteens’ perceived capabilities and their actual competencies and knowledge of the technical, social, and ethical complexities presented online and in the use of devices.  Also evident were inconsistencies in the types of support needed to care for the safety and wellbeing of young people.  This suggests young people continue to need regular and robust support from agencies they themselves identified as important, and included caregivers, schools, and peers. 

Opportunities to further develop caregivers’ skills and knowledge is recommended, so they may better understand the crucial role they have in supporting the safety and wellbeing of their child in their exploration of complex digital environments.  Their role is essential in positively contributing to the development of a concern for privacy.  Recommendations are made, for schools, educators, and education policy makers in their role in this development.  These include sustained teaching and learning opportunities across all learning levels in building related skills and competencies.  Sourcing perspectives from preteens themselves as the experts of their ideas, experiences and knowledge, is integral to understanding how they navigate privacy issues when living lives both offline and online.

year: 2016

title: The alienation of the Opuatia block: A GIS case study report written for Counting our Tūpuna

authors: Whitehead, Jesse

abstract: This report provides an analysis and visualisation of the fragmentation and alienation of the Opuatia block (Opuatia hereafter), as well as changes in its ownership and geographic structure since 1866.
The three main aims are to quantify the amount of Opuatia remaining in Ngāti Tiipa ownership at the end of each decade, identifying critical moments in time, and highlighting the processes through which Opuatia was alienated and fragmented. These questions are addressed through a bespoke method that was developed to link data from several sources. These include (but are not limited to) historic records of land alienation, held by the Māori Land Court, and geospatial information available through Land Information New Zealand.
The key findings show that approximately 94% of the original Opuatia has been alienated, with only small parcles of land remaining in Ngāti Tiipa ownership. The late 1890s and early 1900s were a criticial period where over 80% of alienations were carried out. The results inidcate that the Crown was a key driver of this process, directly alienating more than 18,000 acres from Opuatia, much of which was taken on a single day in 1896. Individual settlers were responsible for most other alienations, and some of the same names appear several times in the historical record as settler families alienated clusters of land to build up significant stakes in the area. Finally, another result of this report is the method itself, which outlines an approach for tracing a defined block of land through the Native Land Court and linking this information to geospatial datasets.
The limitations of this report include the poor interoperability of key data sources, and the barriers that this presents to other hapū or organisations who may want to replicate this work. A more detailed investigation of archival records is required to examine the specific reasons behind why each parent block, and the subdivisions with them, was alienated from Ngāti Tiipa ownership.

text: The alienation of the Opuatia block: A GIS case study report written for Counting our Tūpuna This report provides an analysis and visualisation of the fragmentation and alienation of the Opuatia block (Opuatia hereafter), as well as changes in its ownership and geographic structure since 1866.
The three main aims are to quantify the amount of Opuatia remaining in Ngāti Tiipa ownership at the end of each decade, identifying critical moments in time, and highlighting the processes through which Opuatia was alienated and fragmented. These questions are addressed through a bespoke method that was developed to link data from several sources. These include (but are not limited to) historic records of land alienation, held by the Māori Land Court, and geospatial information available through Land Information New Zealand.
The key findings show that approximately 94% of the original Opuatia has been alienated, with only small parcles of land remaining in Ngāti Tiipa ownership. The late 1890s and early 1900s were a criticial period where over 80% of alienations were carried out. The results inidcate that the Crown was a key driver of this process, directly alienating more than 18,000 acres from Opuatia, much of which was taken on a single day in 1896. Individual settlers were responsible for most other alienations, and some of the same names appear several times in the historical record as settler families alienated clusters of land to build up significant stakes in the area. Finally, another result of this report is the method itself, which outlines an approach for tracing a defined block of land through the Native Land Court and linking this information to geospatial datasets.
The limitations of this report include the poor interoperability of key data sources, and the barriers that this presents to other hapū or organisations who may want to replicate this work. A more detailed investigation of archival records is required to examine the specific reasons behind why each parent block, and the subdivisions with them, was alienated from Ngāti Tiipa ownership.

year: 2021