Modelling systems that integrate programming language and environment mechanisms

Once we relax the assumption that it must be possible to specify programs solely in terms of text and enter them in isolation from other tools, the range of possible program development mechanisms is significantly increased. Thus, in the light of advances in the field of integrated software development environments and in view of the wider availability of suitable workstations, we should reconsider the way we perceive (and, hence design) programming languages. This paper describes on-going work aimed at exploring the role of the programming language in the context of modern software development environments. The work is currently focused on two fronts: the development of a formalism for describing both a programming language and associated environment mechanisms, and the design of environment mechanisms that support software maintenance and reuse, complementing those traditionally provided by programming languages. This paper focuses on work in the first of these two areas

What lies behind the data? How sampling assumptions shape and are shaped by inductive inference

The problems of everyday cognition, from perception to social interaction and higher level reasoning, require us to predict future events and outcomes on the basis of past experience. But often (if not always) solutions to the problems we face are under-determined by our experience. So we reason inductively, drawing uncertain conclusions from incomplete information. Yet, despite our lack of first hand data, our reasoning is efficient and effective nonetheless. So how do we close the gap between the paucity of experience and the effectiveness of reason? One way that we do this is by exploiting statistical regularities that we have observed in the world, assuming (contra philosophers’ counsel) that these regularities will continue to hold. In so doing, we leverage the evidentiary value of the data that we do have. This thesis examines our assumptions about what lies beneath the data and how we leverage them to reason beyond it. In particular, it focuses on our mental models of the world – generative models that connect observations to hypotheses through their consequences. I consider the assumptions we make in solving three separate reasoning problems of increasing complexity. Firstly, in a series of related experiments I explore the effect of sampling assumptions in a categorisation task based on low-dimensional perceptual stimuli. Together, these experiments examine how reasoners weigh the value of extra data when deciding how far to generalise, and the extent to which the computations involved are influenced by their representational and sampling assumptions. In addition, I use the same experimental framework to investigate a related question: if people’s sampling assumptions do alter the weighing of evidence, at what stage do these effects manifest – during learning, or only at the point of generalisation? Secondly, I examine the role of sampling assumptions in the shift from percept to concept. A key challenge for the reasoner when reasoning from high-dimensional categorical stimuli is in deciding which of the many dimensions or features represent the appropriate basis for induction. I investigate how the perceived relevance of particular features in the data is affected by people’s assumptions about the representativeness of the sampling process. In almost every sphere of human activity, we reason from data generated by others and we generate data from which others will reason. Equipped with a theory of mind, both senders and receivers of data may exploit recursive “I think, you think, I think...” reasoning to increase the evidentiary weight of data, and improve the utility of communication as a result. But when data is highly leveraged in this way, there is a downside risk. If reciprocal assumptions are not well calibrated, the reasoner may leap to the wrong conclusion. In the final study, I investigate the phenomena of recursive meta-inference in a setting where deception is warranted but lying is not an option – a setting which offers particular advantages. Firstly, when perpetrating or avoiding a deception, some degree of meta-inferential assumption becomes a vital pre-requisite. Secondly, placing the goals of communicating parties at odds offers the potential to more easily distinguish whether people engage in genuine reflection about the assumptions of another or merely respond to constraints implicit in the sampling process. The studies described in this thesis deal with progressively more complex challenges that we face as reasoners: how far should we generalise when the basis of induction is clear, how do we determine the relevant basis for induction in the first place, and how do we calibrate our own inductive inference with that of another. Through a combination of computational modelling and human behavioural experiments I demonstrate how our sampling assumptions influence the way we meet these challenges, and how our solution to each challenge may be inter-related.Thesis (Ph.D.) -- University of Adelaide, School of Psychology, 201

Inductive reasoning in humans and large language models

The impressive recent performance of large language models has led many to wonder to what extent they can serve as models of general intelligence or are similar to human cognition. We address this issue by applying GPT-3.5 and GPT-4 to a classic problem in human inductive reasoning known as property induction. Over two experiments, we elicit human judgments on a range of property induction tasks spanning multiple domains. Although GPT-3.5 struggles to capture many aspects of human behaviour, GPT-4 is much more successful: for the most part, its performance qualitatively matches that of humans, and the only notable exception is its failure to capture the phenomenon of premise non-monotonicity. Our work demonstrates that property induction allows for interesting comparisons between human and machine intelligence and provides two large datasets that can serve as benchmarks for future work in this vein.Comment: 61 pages, 5 figure

Do sequential lineups impair underlying discriminability?

© 2020, The Author(s). Debate regarding the best way to test and measure eyewitness memory has dominated the eyewitness literature for more than 30 years. We argue that resolution of this debate requires the development and application of appropriate measurement models. In this study we developed models of simultaneous and sequential lineup presentations and used these to compare these procedures in terms of underlying discriminability and response bias, thereby testing a key prediction of diagnostic feature detection theory, that underlying discriminability should be greater for simultaneous than for stopping-rule sequential lineups. We fit the models to the corpus of studies originally described by Palmer and Brewer (2012, Law and Human Behavior, 36(3), 247–255), to data from a new experiment and to eight recent studies comparing simultaneous and sequential lineups. We found that although responses tended to be more conservative for sequential lineups there was little or no difference in underlying discriminability between the two procedures. We discuss the implications of these results for the diagnostic feature detection theory and other kinds of sequential lineups used in current jurisdictions

Five New Millisecond Pulsars From a Radio Survey of 14 Unidentified Fermi-LAT Gamma-ray Sources

We have discovered five millisecond pulsars (MSPs) in a survey of 14 unidentified Fermi-LAT sources in the southern sky using the Parkes radio telescope. PSRs J0101-6422, J1514-4946, and J1902-5105 reside in binaries, while PSRs J1658-5324 and J1747-4036 are isolated. Using an ephemeris derived from timing observations of PSR J0101-6422 (P =2.57 ms, DM=12 pc cm-3), we have detected {\gamma}-ray pulsations and measured its proper motion. Its {\gamma}-ray spectrum (a power law of {\Gamma} = 0.9 with a cutoff at 1.6 GeV) and efficiency are typical of other MSPs, but its radio and {\gamma}-ray light curves challenge simple geometric models of emission. The high success rate of this survey-enabled by selecting {\gamma}-ray sources based on their detailed spectral characteristics-and other similarly successful searches indicate that a substantial fraction of the local population of MSPs may soon be known.Comment: 6 pages, 3 figures, 2 tables, accepted by ApJ

PSR J2030+3641: radio discovery and gamma-ray study of a middle-aged pulsar in the now identified Fermi-LAT source 1FGL J2030.0+3641

In a radio search with the Green Bank Telescope of three unidentified low Galactic latitude Fermi-LAT sources, we have discovered the middle-aged pulsar J2030+3641, associated with 1FGL J2030.0+3641 (2FGL J2030.0+3640). Following the detection of gamma-ray pulsations using a radio ephemeris, we have obtained a phase-coherent timing solution based on gamma-ray and radio pulse arrival times that spans the entire Fermi mission. With a rotation period of 0.2 s, spin-down luminosity of 3e34 erg/s, and characteristic age of 0.5 Myr, PSR J2030+3641 is a middle-aged neutron star with spin parameters similar to those of the exceedingly gamma-ray-bright and radio-undetected Geminga. Its gamma-ray flux is 1% that of Geminga, primarily because of its much larger distance, as suggested by the large integrated column density of free electrons, DM=246 pc/cc. We fit the gamma-ray light curve, along with limited radio polarimetric constraints, to four geometrical models of magnetospheric emission, and while none of the fits have high significance some are encouraging and suggest that further refinements of these models may be worthwhile. We argue that not many more non-millisecond radio pulsars may be detected along the Galactic plane that are responsible for LAT sources, but that modified methods to search for gamma-ray pulsations should be productive -- PSR J2030+3641 would have been found blindly in gamma rays if only >0.8 GeV photons had been considered, owing to its relatively flat spectrum and location in a region of high soft background.Comment: Accepted for publication in ApJ, 9 pages, 6 figure

The High Time Resolution Universe Survey VI: An Artificial Neural Network and Timing of 75 Pulsars

We present 75 pulsars discovered in the mid-latitude portion of the High Time Resolution Universe survey, 54 of which have full timing solutions. All the pulsars have spin periods greater than 100 ms, and none of those with timing solutions are in binaries. Two display particularly interesting behaviour; PSR J1054-5944 is found to be an intermittent pulsar, and PSR J1809-0119 has glitched twice since its discovery. In the second half of the paper we discuss the development and application of an artificial neural network in the data-processing pipeline for the survey. We discuss the tests that were used to generate scores and find that our neural network was able to reject over 99% of the candidates produced in the data processing, and able to blindly detect 85% of pulsars. We suggest that improvements to the accuracy should be possible if further care is taken when training an artificial neural network; for example ensuring that a representative sample of the pulsar population is used during the training process, or the use of different artificial neural networks for the detection of different types of pulsars.Comment: 15 pages, 8 figure

Radio Detection of the Fermi LAT Blind Search Millisecond Pulsar J1311-3430

We report the detection of radio emission from PSR J1311-3430, the first millisecond pulsar discovered in a blind search of Fermi Large Area Telescope (LAT) gamma-ray data. We detected radio pulsations at 2 GHz, visible for <10% of ~4.5-hrs of observations using the Green Bank Telescope (GBT). Observations at 5 GHz with the GBT and at several lower frequencies with Parkes, Nancay, and the Giant Metrewave Radio Telescope resulted in non-detections. We also report the faint detection of a steep spectrum continuum radio source (0.1 mJy at 5 GHz) in interferometric imaging observations with the Jansky Very Large Array. These detections demonstrate that PSR J1311-3430, is not radio quiet and provides additional evidence that the radio beaming fraction of millisecond pulsars is very large. The radio detection yields a distance estimate of 1.4 kpc for the system, yielding a gamma-ray efficiency of 30%, typical of LAT-detected MSPs. We see apparent excess delay in the radio pulsar as the pulsar appears from eclipse and we speculate on possible mechanisms for the non-detections of the pulse at other orbital phases and observing frequencies.Comment: 6 pages, 4 figures. ApJ Letters, in pres

The High Time Resolution Universe Pulsar Survey IV: Discovery and polarimetry of millisecond pulsars

We present the discovery of six millisecond pulsars (MSPs) in the High Time Resolution Universe (HTRU) survey for pulsars and fast transients carried out with the Parkes radio telescope. All six are in binary systems with approximately circular orbits and are likely to have white dwarf companions. PSR J1017-7156 has a high flux density and a narrow pulse width, making it ideal for precision timing experiments. PSRs J1446-4701 and J1125-5825 are coincident with gamma-ray sources, and folding the high-energy photons with the radio timing ephemeris shows evidence of pulsed gamma-ray emission. PSR J1502-6752 has a spin period of 26.7 ms, and its low period derivative implies that it is a recycled pulsar. The orbital parameters indicate it has a very low mass function, and therefore a companion mass much lower than usually expected for such a mildly recycled pulsar. In addition we present polarisation profiles for all 12 MSPs discovered in the HTRU survey to date. Similar to previous observations of MSPs, we find that many have large widths and a wide range of linear and circular polarisation fractions. Their polarisation profiles can be highly complex, and although the observed position angles often do not obey the rotating vector model, we present several examples of those that do. We speculate that the emission heights of MSPs are a substantial fraction of the light cylinder radius in order to explain broad emission profiles, which then naturally leads to a large number of cases where emission from both poles is observed.Comment: Update to correct affiliation for CAASTRO. 16 pages, 18 figures. Accepted for publication in MNRA

Eight gamma-ray pulsars discovered in blind frequency searches of Fermi LAT data

We report the discovery of eight gamma-ray pulsars in blind frequency searches using the LAT, onboard the Fermi Gamma-ray Space Telescope. Five of the eight pulsars are young (tau_c10^36 erg/s), and located within the Galactic plane (|b|<3 deg). The remaining three are older, less energetic, and located off the plane. Five pulsars are associated with sources included in the LAT bright gamma-ray source list, but only one, PSR J1413-6205, is clearly associated with an EGRET source. PSR J1023-5746 has the smallest characteristic age (tau_c=4.6 kyr) and is the most energetic (Edot=1.1E37 erg/s) of all gamma-ray pulsars discovered so far in blind searches. PSRs J1957+5033 and J2055+25 have the largest characteristic ages (tau_c~1 Myr) and are the least energetic (Edot~5E33 erg/s) of the newly-discovered pulsars. We present the timing models, light curves, and detailed spectral parameters of the new pulsars. We used recent XMM observations to identify the counterpart of PSR J2055+25 as XMMU J205549.4+253959. In addition, publicly available archival Chandra X-ray data allowed us to identify the likely counterpart of PSR J1023-5746 as a faint, highly absorbed source, CXOU J102302.8-574606. The large X-ray absorption indicates that this could be among the most distant gamma-ray pulsars detected so far. PSR J1023-5746 is positionally coincident with the TeV source HESS J1023-575, located near the young stellar cluster Westerlund 2, while PSR J1954+2836 is coincident with a 4.3 sigma excess reported by Milagro at a median energy of 35 TeV. Deep radio follow-up observations of the eight pulsars resulted in no detections of pulsations and upper limits comparable to the faintest known radio pulsars, indicating that these can be included among the growing population of radio-quiet pulsars in our Galaxy being uncovered by the LAT, and currently numbering more than 20.Comment: Submitted to Ap