An evaluation of a checklist in Musculoskeletal (MSK) radiographic image interpretation when using Artificial Intelligence (AI)

Background: AI is being used increasingly in image interpretation tasks. There are challenges for its optimal use in reporting environments. Human reliance on technology and bias can cause decision errors. Trust issues exist amongst radiologists and radiographers in both over-reliance (automation bias) and reluctance in AI use for decision support. A checklist, used with the AI to mitigate against such biases, may optimise the use of AI technologies and promote good decision hygiene. Method: A checklist, to be used in image interpretation with AI assistance, was developed. Participants interpreted 20 examinations with AI assistance and then re- interpreted the 20 examinations with AI and a checklist. The MSK images were presented to radiographers as patient examinations to replicate the image interpretation task in clinical practice. Image diagnosis and confidence levels on the diagnosis provided were collected following each interpretation. The participant perception of the use of the checklist was investigated via a questionnaire.Results: Data collection and analysis are underway and will be completed at the European Congress of Radiology in Vienna, March 2023. The impact of the use of a checklist in image interpretation with AI will be evaluated. Changes in accuracy and confidence will be investigated and results will be presented. Participant feedback will be analysed to determine perceptions and impact of the checklist also. Conclusion: A novel checklist has been developed to aid the interpretation of images when using AI. The checklist has been tested for its use in assisting radiographers in MSK image interpretation when using AI.<br/

LIPIcs, Volume 261, ICALP 2023, Complete Volume

LIPIcs, Volume 261, ICALP 2023, Complete Volum

Complexity results and integer programming models for hospitals / residents problem variants

The classical Hospitals / Residents problem (HR) is a many-to-one bipartite matching problem involving preferences, motivated by centralised matching schemes arising in entry level labour markets, the assignment of pupils to schools and higher education admissions schemes, among its many applications. The particular requirements of these matching schemes may lead to generalisations of HR that involve additional inputs or constraints on an acceptable solution. In this thesis we study such variants of HR from an algorithmic and integer programming viewpoint. The Hospitals / Residents problem with Couples (HRC) is a variant of HR that is important in practical applications because it models the case where couples submit joint preference lists over pairs of (typically geographically close) hospitals. It is known that an instance of HRC need not admit a stable matching. We show that deciding whether an instance of HRC admits a stable matching is NP-complete even under some very severe restrictions on the lengths and the structure of the participants’ preference lists. However, we show that under certain restrictions on the lengths of the agents’ preference lists, it is possible to find a maximum cardinality stable matching or report that none exists in polynomial time. Since an instance of HRC need not admit a stable matching, it is natural to seek the ‘most stable’ matching possible, i.e., a matching that admits the minimum number of blocking pairs. We use a gap-introducing reduction to establish an inapproximability bound for the problem of finding a matching in an instance of HRC that admits the minimum number of blocking pairs. Further, we show how this result might be generalised to prove that a number of minimisation problems based on matchings having NP-complete decision versions have the same inapproximability bound. We also show that this result holds for more general minimisation problems having NP-complete decisions versions that are not based on matching problems. Further, we present a full description of the first Integer Programming (IP) model for finding a maximum cardinality stable matching or reporting that none exists in an arbitrary instance of HRC. We present empirical results showing the average size of a maximum cardinality stable matching and the percentage of instances admitting stable matching taken over a number of randomly generated instances of HRC with varying properties. We also show how this model might be generalised to the variant of HRC in which ties are allowed in either the hospitals’ or the residents’ preference lists, the Hospitals / Residents problem with Couples and Ties (HRCT). We also describe and prove the correctness of the first IP model for finding a maximum cardinality ‘most stable’ matching in an arbitrary instance of HRC. We describe empirical results showing the average number of blocking pairs admitted by a most-stable matching as well as the average size of a maximum cardinality ‘most stable’ matching taken over a number of randomly generated instances of HRC with varying properties. Further, we examine the output when the IP model for HRCT is applied to real world instances arising from the process used to assign medical graduates to Foundation Programme places in Scotland in the years 2010-2012. The Hungarian Higher Education Allocation Scheme places a number of additional constraints on the feasibility of an allocation and this gives rise to various generalisations of HR. We show how a number of these additional requirements may be modelled using IP techniques by use of an appropriate combination of IP constraints. We present IP models for HR with Stable Score Limits and Ties, HR with Paired Applications, Ties and Stable Score limits, HR with Common Quotas, Ties and Stable Score Limits and also HR with Lower Quotas, Ties and Stable Score limits that model these generalisations of HR. The Teachers’ Allocation Problem (TAP) is a variant of HR that models the allocation of trainee teachers to supervised teaching positions in Slovakia. In TAP teachers express preference lists over pairs of subjects at individual schools. It is known that deciding whether an optimal matching exists that assigns all of the trainee teachers is NP-complete for a number of restricted cases. We describe IP models for finding a maximum cardinality matching in an arbitrary TAP instance and for finding a maximum cardinality stable matching, or reporting that none exists, in a TAP instance where schools also have preferences. We show the results when applying the first model to the real data arising from the allocation of trainee teachers to schools carried out at P.J. Safarik University in Kosice in 2013

Housing quality and lost (public) space in Croatia

IN ENGLISH: In the post-socialist period and within the current social transition context, urban and rural Croatia has, just like other transition countries, experienced many changes in the social structure and space. One example is the housing quality which is a replica of the situation in the Croatian society and has also undergone some major changes. Socially oriented housing construction co-financed by the state and the cities is in an unfavourable position compared to private housing construction. In the last twenty years the amount of the social housing construction has been only a minor part of the total contruction work in the country. For instance, out of nine newly planned residential housing developments in Zagreb, the capital city, only three have been completed and the work on the rest of them has stopped and is unlikely to continue. Private construction work prevails especially on the edge of the city and is characterised by high density housing. This type of housing construction doesn't benefit the majority of citizens in search of accommodation (price per square meter is too high, low-quality building). There is also a big problem of the community facilities (primary and secondary infrastructure, schools, kindergartens, playgrounds, green areas, sidewalks, public transport etc.). The existing globalisation-transition circumstances of the Croatian society corroborate the fact which experts of various profiles often point out: ignoring the process of (urban) planning will irreparably damage the space. The city transformation shows the absence of comprehensive urban planning which results in an ever increasing number of random buildings which do not fit in the surroundings. This leads up to yet another important issue – the shrinking and, in some cases, disappearance of public space which becomes the “lost space“. In recent years there has been a lot of building in the city core and on the edge which does not quite fit in the existing urban structure, image or the skyline of the city. The current situation in the process of planning can be characterized as a conflict and imbalance between the powerful actors (mostly political and economic) and less powerful actors (mostly professional and civil). The actors who have the political power and influence and the ones who possess the capital are forming an “alliance” between two important layers of the social structure. The lack of civil and professional actors, “lost spatial actors”, and therefore of civic aggregation is also present and that is also the cause of public space “disappearance” and undermined process of public participation. --------------- IN CROATIAN: U postsocijalističkom razdoblju i trenutnom tranzicijskom kontekstu urbana i ruralna Hrvatska su, kao i ostale tranzicijske zemlje, doživjele mnoge promjene u društvenoj strukturi i samom prostoru. Na primjeru kvalitete stanovanja kao replike stanja u hrvatskom društvu mogu se vidjeti značajne promjene. Društveno usmjerena stambena izgradnja sufinancirana od strane države i gradova je stoga rjeđa i u nepovoljnijoj je situaciji prema privatnoj stanogradnji. Zadnjih dvadeset godina udjel socijalne stambene gradnje je zanemariv u ukupnoj izgradnji na razini zemlje. Primjerice, od devet planiranih stambenih naselja izgrađenih po modelu POS-a u Zagrebu samo su tri i završena. Na ostalima je proces gradnje zastao i ne čini se da će se privesti kraju. Privatna je gradnje prisutnija, posebno na rubovima grada, a obilježava je visoka gustoća gradnje. Ovakav tip gradnje ne odgovara većini stanovnika koji su u procesu potražnje stambene nekretnine (visoka cijena kvadratnog metra, a slaba kvaliteta gradnje). Postoji također i problem nedostatne opremljenosti susjedstva (primarna i sekundarna infrastruktura, škole, vrtići, igrališta, zelene površine, pješačke staze, javni transport itd.). Navedene globalizacijsko-tranzicijske okolnosti hrvatskog društva potvrđuju ono što eksperti različitih profila ističu, a to je da će ignoriranje procesa (urbanog) planiranja nepovratno uništiti prostor gradova. Ovakve transformacije pokazuju nedostatak sustavnog urbanog planiranja što rezultira sve većim brojem zgrada koje se ne uklapaju u neposrednu okolinu. To nadalje dovodi do drugog važnog aspekta – smanjivanja i u nekim slučajevima, nestanka javnog prostora koji postaje „izgubljeni prostor“. Posljednjih je godina izgrađen velik broj zgrada, i u središtu i na rubovima grada, koje se ne uklapaju u postojeću urbanu strukturu, izgled ili vizuru grada. Ovakvu situaciju obilježavaju sukob i neravnoteža između moćnijih društvenih aktera (većinom političkih i ekonomskih) i onih manje moćnih (većinom profesionalnih i civilnih). Politički i ekonomski akteri se često povezuju u „savez“ dvaju najjačih u društvenoj strukturi. S druge strane nedostatak utjecaja civilnih i profesionalnih aktera kao „izgubljenih prostornih aktera“ dovodi do „nestanka“ javnih prostora te smanjenja važnosti procesa participacije (sudjelovanja javnosti)

2-μερή και πολύ-μερή ευσταθή ταιριάσματα: δομές, αλγόριθμοι και εφαρμογές

This thesis examines the Stable Matching problem (SM) and some of its most important variants, namely the Stable Admissions (SAX the many-to-many Stable Matching (MM), and the Chain Stable Network problem. In the context of the SM, a time-optimal algorithm is provided that identifies which of the non-stable pairs can be removed from the agents' preference lists without altering the set of solutions. Then, using a directed line-graph to represent the SM, a sparse description of the SM polytope is derived. This description is further reduced to obtain the minimal one by identifying the minimal equation system and the facets of the corresponding polytope. Also, the dimension of the SM polytope is proved to be equal to the number of rotations, while its diameter is also established. Moreover, the alternative rotation-based representation of the SM polytope is also examined. Further, rotations are defined in the SA setting and a time-optimal algorithm for identifying all rotations and all non-stable pairs is proposed. This algorithm is then extended to the MM case under pairwise stability, preferences over individuals, and the max-min criterion. In order to maintain the algorithms optimal complexity, the use of a double-stack is proposed. Next, the corresponding rotation-poset graph is revisited and a time- and space-optimal algorithm for enumerating all solutions to the MM is illustrated. Then, a polynomial algorithm for finding the minimum-weight stable matching is provided, which is shown to be applicable even in the case of more complex preference and stability conditions. In a Constraint Programming (CP) context, it is shown that identifying all stable pairs in the SA and the MM case is equivalent to establishing hyperarc consistency. Furthermore, a predicate which models the MM and its encoding as a Constraint Satisfaction Problem is provided. Also, establishing hyperarc consistency as a preprocessing step in a CP platform is proposed, thus obtaining an efficient programming tool, especially in the case where side-constraints are present. Last, a multi-sided Supply Chain Network (SCN) configuration is examined. Under this reduced setting, it is proved that every such £-sided SCN can be decomposed into k-1 independent SM sub-markets. Moreover, it is shown that the set of chain stable networks forms a distributive lattice. Furthermore, the notion of contract-rotations is defined and a series of specialized algorithms are proposed.Η διατριβή αυτή εξετάζει το πρόβλημα του Ευσταθούς Ταιριάσματος (ET), της Ευσταθούς Εισαγωγής (ΕΕ), του πολλά-προς-πολλά Ευσταθούς Ταιριάσματος (ΊΊΠ) και της Ευσταθούς Εφοδιαστικής Αλυσίδας (ΕΕΑ). Στα πλαίσια του ET, παρέχεται ένας χρονικά βέλτιστος αλγόριθμος που αναγνωρίζει ποια από τα μη ευσταθή ζεύγη μπορούν να αφαιρεθούν από τις λίστες προτίμησης χωρίς να προκαλέσουν αλλαγές στο σύνολο των λύσεων. Επιπλέον, χρησιμοποιώντας ένα κατευθυνόμενο γραμμογράφημα και το μειωμένο γράφημα περιστροφών, δίνεται η ελάχιστη περιγραφή του πολυτόπου του ET. Επιπλέον, η διάσταση του αποδεικνύεται ότι είναι ίση με τον αριθμό των περιστροφών, ενώ υπολογίζεται και η διάμετρος του. Ακόμα, εξετάζεται και η εναλλακτική αναπαράσταση του πολυτόπου αυτού που βασίζεται στις περιστροφές. Επίσης, οι περιστροφές ορίζονται στα πλαίσια του ΕΕ, όπου δίνεται ένας χρονικά βέλτιστος αλγόριθμος για την αναγνώριση όλων των περιστροφών και των μη ευσταθών ζευγών. Ο αλγόριθμος αυτός επεκτείνεται και στην περίπτωση του ΠΠ υπό ζευγωτή ευστάθεια, ατομικές προτιμήσεις και το κριτήριο max-min. Μάλιστα, η χρήση μιας διπλής στοίβας προτείνεται για την διατήρηση της βελτιστότητας του αλγορίθμου αυτού. Στη συνέχεια, επανεξετάζονται οι κανόνες κατασκευής του γραφήματος περιστροφών και παρέχεται ένας χρονικά και χωρικά βέλτιστος αλγόριθμος για την απαρίθμηση όλων των λύσεων. Επιπλέον, παρέχεται ένας πολυωνυμικός αλγόριθμος για την εύρεση της λύσης ελαχίστου βάρους, ο οποίος αποδεικνύεται ότι μπορεί να εφαρμοστεί ακόμα και σε περιπτώσεις με πιο περίπλοκες συνθήκες προτιμήσεων και ευστάθειας. Στα πλαίσια του προγραμματισμού περιορισμών (ΉΕ), αποδεικνύεται ότι η αναγνώριση όλων των ευσταθών ζευγών στην περίπτωση του ΕΕ και του ΠΠ ισοδυναμεί με την επίτευξη συνέπειας υπερακμής. Επίσης, παρουσιάζεται ένας περιορισμός ο οποίος μοντελοποιεί το ΠΠ καθώς και η κωδικοποίηση του ως πρόβλημα ικανοποίησης περιορισμών. Επιπλέον, προτείνεται η χρήση του αλγορίθμου που επιτυγχάνει συνέπεια υπερακμής ως ένα προ-επεξεργαστικό βήμα σε μια πλατφόρμα ΠΕ. Η μέθοδος αυτή καταδεικνύεται ότι είναι ιδιαίτερα αποτελεσματική, ιδίως υπό την παρουσία επιπλέον περιορισμών. Τέλος, μελετάται μια εξειδικευμένη εκδοχή του ΕΕΑ. Αποδεικνύεται ότι μία εφοδιαστική αλυσίδα με k σύνολα μπορεί να διαιρεθεί σε k-1 ανεξάρτητες αγορές ET, ενώ η κλίμακα που δημιουργείται από το σύνολο των λύσεων είναι κατανεμημένη. Επιπλέον, ορίζεται η έννοια της περιστροφής συμβολαίων, και παρέχεται μια σειρά από σχετικούς εξειδικευμένους αλγορίθμους