Software pirates: a criminal investigation

Computer program infringing materials are difficult to identify. There are common techniques to disguise the origin of copied codes. In order to decide on a legal basis whether a substantial part of copyright work has been taken, it is necessary to consider both the quality and quantity of the part taken. Various researches have carried out in relation to authorship identification and plagiarism identification. In a criminal case in Hong Kong, we used a common software to compare files contents and folders between a copyright work and the infringing copy instead of complex and technical metrics. We conclude that the source codes of the defendant started from the source codes of his previous employer using simple and easy to understand measurements. Though the magistrate was satisfied beyond reasonable doubt of the defendant’s guilt, the evidence in the case did not enable a scientific calculation in respect of the likelihood that a computer program may look like a derivative of another program by chance.postprintThe 33rd ACM SIGPLAN Conference on Programming Language Design and Implementation (PLDI 2012), Beijing, China, 11-16 June 2012. In Proceedings of the PLDI, 2012, p. 1-1

A battle of wits? Problem-solving abilities in invasive Eastern grey squirrels and native Eurasian red squirrels

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordBehavioural flexibility has been argued to be an evolutionarily favourable trait that helps invasive species to establish themselves in non-native environments. Few studies, however, have compared the level of flexibility (whether considered as an outcome or as a process) in mammalian invaders and related native species. Here, we tested whether flexibility differs between groups of free-ranging invasive eastern grey squirrels, Sciurus carolinensis, and native Eurasian red squirrels, Sciurus vulgaris, in the U.K., using an easy and a difficult food extraction task. All individuals of both species showed flexibility, at the outcome level, in solving the easy task and solution time was comparable between species across a series of successes. A higher proportion of grey squirrels than red squirrels solved the difficult task. However, for those squirrels that did solve the task, solving efficiency was comparable between species on their first success, and a few red squirrels outperformed the grey squirrels in subsequent successes. Between-species analysis showed that instantaneous flexibility, flexibility at the process level that was measured as the rate of switching between tactics after a failed attempt, was higher in red squirrels than in grey squirrels. Within-species analysis also revealed that red squirrel problem solvers showed higher flexibility at the process level than their nonsolver counterparts. Nonsolvers also failed to make ‘productive’ switches (switching from ineffective to effective tactics). Together, the results suggest that problem-solving ability overlaps in the two species, but is less variable, and on average higher, in grey squirrels than in red squirrels. The superior behavioural flexibility of the grey squirrels, shown here by success at problem solving, may have facilitated their invasion success, but it may also have resulted from selective pressures during the invasion process.This project is supported by the Postgraduate Research Enhancement Fund from University of Exeter and Gilbert’s private fund

Touch screen assays of behavioural flexibility and error characteristics in Eastern grey squirrels (Sciurus carolinensis)

This is the final version of the article. Available from the publisher via the DOI in this record.Behavioural flexibility allows animals to adjust their behaviours according to changing environmental demands. Such flexibility is frequently assessed by the discrimination–reversal learning task. We examined grey squirrels’ behavioural flexibility, using a simultaneous colour discrimination–reversal learning task on a touch screen. Squirrels were trained to select their non-preferred colour in the discrimination phase, and their preferred colour was rewarded in a subsequent reversal phase. We used error rates to divide learning in each phase into three stages (perseveration, chance level and ‘learned’) and examined response inhibition and head-switching during each stage. We found consistent behavioural patterns were associated with each learning stage: in the perseveration stage, at the beginning of each training phase, squirrels showed comparable response latencies to correct and incorrect stimuli, along with a low level of head-switching. They quickly overcame perseveration, typically in one to three training blocks. In the chance-level stage, response latencies to both stimuli were low, but during initial discrimination squirrels showed more head-switches than in the previous stage. This suggests that squirrels were learning the current reward contingency by responding rapidly to a stimulus, but with increased attention to both stimuli. In the learned stage, response latencies to the correct stimulus and the number of head-switches were at their highest, whereas incorrect response latencies were at their lowest, and differed significantly from correct response latencies. These results suggest increased response inhibition and attention allowed the squirrels to minimise errors. They also suggest that errors in the ‘learned’ stage were related to impulsive emission of the pre-potent or previously learned responses

Serial reversal learning in Gray Squirrels: learning efficiency as a function of learning and change of tactics

This is the author accepted manuscript. The final version is available from American Psychological Association via the DOI in this record.Learning allows individuals to adapt their behaviors flexibly to a changing environment. When the same change recurs repeatedly, acquiring relevant tactics may increase learning efficiency. We examined this relationship, along with the effects of proactive interference and other interference information, in a serial spatial reversal task with 5 gray squirrels (Sciurus carolinensis). Squirrels completed an acquisition and 11 reversal phases with a poke box in which 2 of 4 possible reward locations were baited diagonally in a square array. In this situation, an efficient tactic is to locate the diagonally related locations consecutively (integrative search tactic) instead of searching rewards in a clockwise or counterclockwise direction (sequential search tactic). All squirrels formed a learning set, acquiring successive reversals in fewer trials. Although 4 squirrels gradually employed more integrative tactics in locating the rewards both within and between phases, sequential tactics were used in the first trial of each phase. This suggests the integrative tactic did not depend on an association between the rewarded locations but was learned as a spatial pattern and/or by use of extra-apparatus cues to locate individual rewards. Generalized estimating equation models showed that learning efficiency increased with experience and tactic change. Although tactic change partially mediated the effect of learning on learning efficiency, learning was an independent contribution to improved efficiency. Squirrels that used more integrative tactics made fewer total errors than squirrels that used less integrative tactics, suggesting that learning a task-relevant tactic using spatial cues can provide direct benefits in maximizing rewards and minimizing time costs

How practice makes perfect: the role of persistence, flexibility and learning in problem solving efficiency

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.To fully understand how problem solving ability provides adaptive advantages for animals, we should understand the mechanisms that support this ability. Recent studies have highlighted several behavioural traits including persistence, behavioural variety and behavioural/cognitive flexibility that contribute to problem solving success. However, any increment in these traits will increase time and energy costs in natural conditions, so they are not necessarily advantageous. To examine how behavioural traits vary during learning to solve a problem efficiently, we gave grey squirrels (Sciurus carolinensis) a problem solving task that required squirrels to obtain out-of-reach but visible hazelnuts by making a lever drop in the laboratory. We recorded persistence, measured as attempt rate, flexibility, measured as the rate of switching between tactics, and behavioural selectivity, measured as the proportion of effective behaviours, in relation to problem solving efficiency on a trial-by-trial basis. Persistence and behavioural selectivity were found to be directly associated with problem solving efficiency. These two factors also mediated the effects of flexibility and increased experience. We also found two routes that led to more efficient problem solving across learning trials: increasing persistence or increasing behavioural selectivity. Flexibility was independent from learning. Flexibility could increase problem solving efficiency, but it also has a time cost; furthermore it seemed to involve a trade-off with behavioural selectivity, with high flexibility being associated with a higher frequency of some disadvantageous ineffective behaviours. These results suggest that flexibility is an independent cognitive process or behavioural trait that may not always bring advantages to animals

How to stay perfect: the role of memory and behavioural traits in an experienced problem and a similar problem

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.When animals encounter a task they have solved previously, or the same problem appears in a different apparatus, how does memory, alongside behavioural traits such as persistence, selectivity and flexibility, enhance problem-solving efficiency? We examined this question by first presenting grey squirrels with a puzzle 22 months after their last experience of it (the recall task). Squirrels were then given the same problem presented in a physically different apparatus (the generalisation task) to test whether they would apply the previously learnt tactics to solve the same problem but in a different apparatus. The mean latency to success in the first trial of the recall task was significantly different from the first exposure but not different from the last exposure of the original task, showing retention of the task. A neophobia test in the generalisation task suggested squirrels perceived the different apparatus as a different problem, but they quickly came to apply the same effective tactics as before to solve the task. Greater selectivity (the proportion of effective behaviours) and flexibility (the rate of switching between tactics) both enhanced efficiency in the recall task, but only selectivity enhanced efficiency in the generalisation task. These results support the interaction between memory and behavioural traits in problem-solving, in particular memory of task-specific tactics that could enhance efficiency. Squirrels remembered and emitted task-effective tactics more than ineffective tactics. As a result, they consistently changed from ineffective to effective behaviours after failed attempts at problem-solving

Inhibitory control and memory in the search process for a modified problem in grey squirrels, Sciurus carolinensis

This is the final version. Available on open access from Springer via the DOI in this recordInhibiting learned behaviours when they become unproductive and searching for an alternative solution to solve a familiar but different problem are two indicators of flexibility in problem solving. A wide range of animals show these tendencies spontaneously, but what kind of search process is at play behind their problem-solving success? Here, we investigated how Eastern grey squirrels, Sciurus carolinensis, solved a modified mechanical problem that required them to abandon their preferred and learned solution and search for alternative solutions to retrieve out-of-reach food rewards. Squirrels could solve the problem by engaging in either an exhaustive search (i.e., using trial-and-error to access the reward) or a ‘backup’ solution search (i.e., recalling a previously successful but non-preferred solution). We found that all squirrels successfully solved the modified problem on their first trial and showed solving durations comparable to their last experience of using their preferred solution. Their success and high efficiency could be explained by their high level of inhibitory control as the squirrels did not persistently emit the learned and preferred, but now ineffective, pushing behaviour. Although the squirrels had minimal experience in using the alternative (non-preferred) successful solution, they used it directly or after one or two failed attempts to achieve success. Thus, the squirrels were using the ‘backup’ solution search process. Such a process is likely a form of generalisation which involves retrieving related information of an experienced problem and applying previous successful experience during problem solving. Overall, our results provide information regarding the search process underlying the flexibility observable in problem-solving success

Sensitivity analysis of a Bayesian network for reasoning about digital forensic evidence

Bayesian network representing an actual prosecuted case of illegal file sharing over a peer-to-peer network has been subjected to a systematic and rigorous sensitivity analysis. Our results demonstrate that such networks are usefully insensitive both to the occurrence of missing evidential traces and to the choice of conditional evidential probabilities. The importance of this finding for the investigation of digital forensic hypotheses is highlighted. © 2010 IEEE.published_or_final_versio

Memory acquisition: A 2-Take approach

When more and more people recognize the value of volatile data, live forensics gains more weight in digital forensics. It is often used in parallel with traditional pull-the-plug forensics to provide a more reliable result in forensic examination. One of the core components in live forensics is the collection and analysis of memory volatile data, during which the memory content is acquired for searching of relevant evidential data or investigating various computer processes to unveil the activities being performed by a user. However, this conventional method may have weaknesses because of the volatile nature of memory data and the absence of original data for validation. This may cause implication to the admissibility of memory data at the court of law which requires strict authenticity and reliability of evidence. In this paper, we discuss the impact of various memory acquisition methods and suggest a 2-Take approach which aims to enhance the confidence level of the acquired memory data for legal proceedings. © 2009 IEEE.published_or_final_versionThe 2009 International Workshop on Forensics for Future Generation Communication Environments (F2GC-09) in conjunction with CSA 2009, Jeju Island, Korea, 10-12 December 2009. In Proceedings of CSA, 2009, p. 1-

Analyzing storage media of digital camera

Digital photography has become popular in recent years. Photographs have become common tools for people to record every tiny parts of their daily life. By analyzing the storage media of a digital camera, crime investigators may extract a lot of useful information to reconstruct the events. In this work, we will discuss a few approaches in analyzing these kinds of storage media of digital cameras. A hypothetical crime case will be used as case study for demonstration of concepts. © 2009 IEEE.published_or_final_versionThe 2009 International Workshop on Forensics for Future Generation Communication Environments (F2GC-09) in conjunction with CSA 2009, Jeju Island, Korea, 10-12 December 2009. In Proceedings of CSA, 2009, p. 1-