Dr Debasis Ganguly
- Lecturer in Data Science (School of Computing Science)
email:
Debasis.Ganguly@glasgow.ac.uk
Room M111, Computing Science, Sir Alwyn Williams Bldg, Glasgow, G12 8QQ
Publications
2024
Sinhababu, N., Parry, A., Ganguly, D. , Samanta, D. and Mitra, P. (2024) Few-shot Pairwise Ranking Prompting: An Effective Non-Parametric Retrieval Model. In: 2024 Conference on Empirical Methods in Natural Language Processing, Miami, Florida, USA, 12–16 November 2024, (Accepted for Publication)
Parry, A., MacAvaney, S. and Ganguly, D. (2024) Top-Down Partitioning for Efficient List-Wise Ranking. In: ReNeuIR'24, Washington, DC, USA, 18 July 2024, (Accepted for Publication)
Parry, A., MacAvaney, S. and Ganguly, D. (2024) Exploiting Positional Bias for Query-Agnostic Generative Content in Search. In: 62nd Annual Meeting of the Association for Computational Linguistics (ACL 2024), Bangkok, Thailand, 11-16 August 2024, (Accepted for Publication)
Santra, P., Ghosh, M., Ganguly, D. , Basuchowdhuri, P. and Naskar, S. K. (2024) "The absence of evidence is not the evidence of absence": Fact Verification via Information Retrieval-based In-Context Learning. In: 26th International Conference on Big Data Analytics and Knowledge Discovery (DAWAK 2024), Naples, Italy, 26-28 August 2024, (Accepted for Publication)
Ghosh, M., Mukherjee, S., Ganguly, A., Basuchowdhuri, P., Naskar, S. K. and Ganguly, D. (2024) AlpaPICO: Extraction of PICO frames from clinical trial documents using LLMs. Methods, 226, pp. 78-88. (doi: 10.1016/j.ymeth.2024.04.005) (PMID:38643910)
Parry, A., Ganguly, D. and Chandra, M. (2024) In-Context Learning or: How I Learned to Stop Worrying and Love Applied Information Retrieval. In: 47th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2024), Washington D.C., USA, 14-18 Jul 2024, (Accepted for Publication)
Vanneste, J., Verma, M. and Ganguly, D. (2024) Detecting and Explaining Emotions in Video Advertisements. In: 47th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2024), Washington D.C., USA, 14-18 Jul 2024, (Accepted for Publication)
Santra, P., Ghosh, M., Mukherjee, S., Ganguly, D. , Basuchowdhuri, P. and Naskar, S. K. (2024) Unleashing the Power of Large Language Models: A Hands-On Tutorial. In: 15th Annual Meeting of the Forum for Information Retrieval Evaluation, Panjim, Goa, India, 15-18 Dec 2023, pp. 149-152. ISBN 9798400716324 (doi: 10.1145/3632754.3632943)
Satapara, S., Mehta, P., Modha, S. and Ganguly, D. (2024) Indian Language Summarization at FIRE 2023. In: 15th Annual Meeting of the Forum for Information Retrieval Evaluation, Panjim, Goa, India, 15-18 Dec 2023, pp. 27-29. (doi: 10.1145/3632754.3634662)
2023
Pandian, S., Ganguly, D. and MacAvaney, S. (2023) Evaluating the Explainability of Neural Rankers. In: 46th European Conference on Information Retrieval (ECIR2024), Glasgow, Scotland, 24-28 March 2024, (Accepted for Publication)
Datta, S., Ganguly, D. , MacAvaney, S. and Greene, D. (2023) A Deep Learning Approach for Selective Relevance Feedback. In: 46th European Conference on Information Retrieval (ECIR2024), Glasgow, Scotland, 24-28 March 2024, (Accepted for Publication)
Adhikary, S., Roy, D., Ganguly, D. , Kumar Guha, S. and Ghosh, K. (2023) LeDA: a system for legal data annotation. In: Sileno, G., Spanakis, J. and van Dijck, G. (eds.) Legal Knowledge and Information Systems. Series: Frontiers in artificial intelligence and applications (379). IOS Press, pp. 370-367. ISBN 9781643684734 (doi: 10.3233/faia230990)
Chandra, M., Ganguly, D. , Saha, T. and Ounis, I. (2023) 'Choose Your Data Wisely’: Active Learning based Selection with Multi-Objective Optimisation for Mitigating Stereotypes. In: 32nd ACM International Conference on Information and Knowledge Management (CIKM 2023), Birmingham, UK, 21-25 Oct 2023, pp. 3768-3772. ISBN 9798400701245 (doi: 10.1145/3583780.3615261)
Ghosh, M., Ganguly, D. , Basuchowdhuri, P. and Kumar Naskar, S. (2023) Extracting Methodology Components from AI Research Papers: A Data-driven Factored Sequence Labeling Approach. In: 32nd ACM International Conference on Information and Knowledge Management (CIKM 2023), Birmingham, UK, 21-25 Oct 2023, pp. 3897-3901. ISBN 9798400701245 (doi: 10.1145/3583780.3615258)
Saha, T., Ganguly, D. , Saha, S. and Mitra, P. (2023) Workshop on Large Language Models' Interpretability and Trustworthiness (LLMIT). In: 32nd ACM International Conference on Information and Knowledge Management (CIKM 2023), Birmingham, UK, 21-25 Oct 2023, pp. 5290-5293. ISBN 9798400701245 (doi: 10.1145/3583780.3615311)
Ganguly, D. and Yilmaz, E. (2023) Query-Specific Variable Depth Pooling via Query Performance Prediction. In: 46th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR23), Taipei, Taiwan, 23-27 July 2023, pp. 2303-2307. ISBN 9781450394086 (doi: 10.1145/3539618.3592046)
Llordes, M., Ganguly, D. , Bhatia, S. and Agarwal, C. (2023) Explain Like I am BM25: Interpreting a Dense Model’s Ranked-List with a Sparse Approximation. In: 46th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR23), Taipei, Taiwan, 23-27 July 2023, pp. 1976-1980. ISBN 9781450394086 (doi: 10.1145/3539618.3591982)
Singh, A., Ganguly, D. , Datta, S. and McDonald, C. (2023) Unsupervised Query Performance Prediction for Neural Models with Pairwise Rank Preferences. In: 46th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR23), Taipei, Taiwan, 23-27 July 2023, pp. 2486-2490. ISBN 9781450394086 (doi: 10.1145/3539618.3592082)
Datta, S., Ganguly, D. , Mitra, M. and Greene, D. (2023) A relative information gain-based query performance prediction framework with generated query variants. ACM Transactions on Information Systems, 41(2), 38. (doi: 10.1145/3545112)
Datta, S., Ganguly, D. , Greene, D. and Mitra, M. (2023) On the Feasibility and Robustness of Pointwise Evaluation of Query Performance Prediction. In: QPP++ 2023: Query Performance Prediction and Its Evaluation in New Tasks, Dublin, Ireland, 06 Apr 2023, pp. 7-12.
Datta, S., Ganguly, D. , Mothe, J. and Ullah, M. Z. (2023) Combining Word Embedding Interactions and LETOR Feature Evidences for Supervised QPP. In: QPP++ 2023: Query Performance Prediction and Its Evaluation in New Tasks, Dublin, Ireland, 06 Apr 2023, pp. 13-19.
Ganguly, D. , Conrad, J. G., Ghosh, K., Ghosh, S., Goyal, P., Bhattacharya, P., Nigam, S. K. and Paul, S. (2023) Legal IR and NLP: The History, Challenges, and State-of-the-Art. In: 45th European Conference on Information Retrieval (ECIR 2023), Dublin, Ireland, 02-06 Apr 2023, pp. 331-340. ISBN 9783031282409 (doi: 10.1007/978-3-031-28241-6_34)
Ganguly, D. , Parker, A. and Aji Mattew, S. (2023) Automatic Videography Generation from Audio Tracks. In: 45th European Conference on Information Retrieval (ECIR'23), Dublin, Ireland, 02-06 Apr 2023, pp. 281-287. ISBN 9783031282409 (doi: 10.1007/978-3-031-28241-6_27)
2022
Jones, G. J.F., Sen, P., Ganguly, D. and Yilmaz, E. (2022) Workshop on Proactive and Agent-Supported Information Retrieval (PASIR). In: CIKM '22: The 31st ACM International Conference on Information and Knowledge Management, Atlanta, GA, US, 17-21 Oct 2022, pp. 5167-5168. ISBN 9781450392365 (doi: 10.1145/3511808.3557939)
Sen, P., Saha, S., Ganguly, D. , Verma, M. and Roy, D. (2022) Measuring and Comparing the Consistency of IR Models for Query Pairs with Similar and Different Information Needs. In: 31st ACM International Conference on Information and Knowledge Management (CIKM '22), Atlanta, Georgia, USA, 17-21 October 2022, pp. 4449-4453. ISBN 9781450392365 (doi: 10.1145/3511808.3557637)
Sen, P., Ganguly, D. and Jones, G. J.F. (2022) I know what you need: investigating document retrieval effectiveness with partial session contexts. ACM Transactions on Information Systems, 40(3), pp. 1-30. (doi: 10.1145/3488667)
Datta, S., MacAvaney, S. , Ganguly, D. and Greene, D. (2022) A 'Pointwise-Query, Listwise-Document' based Query Performance Prediction Approach. In: SIGIR 2022: 45th International ACM SIGIR Conference on Research and Development in Information Retrieval, Madrid, Spain, 11-15 Jul 2022, pp. 2148-2153. ISBN 9781450387323 (doi: 10.1145/3477495.3531821)
Sen, P., Mishra, S., Ganguly, D. and Majumder, P. (2022) A Combination of 'Intra and Inter Collection' Relevance Models for Ad-hoc Retrieval in Precision Medicine. CIRCLE 2022, Toulouse, France, 04-07 Jul 2022.
Ganguly, D. , Datta, S., Mitra, M. and Greene, D. (2022) An Analysis of Variations in the Effectiveness of Query Performance Prediction. In: 44th European Conference on Information Retrieval (ECIR 2022), Stavanger, Norway, 10-14 Apr 2022, pp. 215-229. ISBN 9783030997359 (doi: 10.1007/978-3-030-99736-6_15)
Datta, S., Ganguly, D. , Greene, D. and Mitra, M. (2022) Deep-QPP: a Pairwise Interaction-based Deep Learning Model for Supervised Query Performance Prediction. In: WSDM '22: 15th ACM International Conference on Web Search and Data Mining, 21-25 Feb 2022, pp. 201-209. ISBN 9781450391320
Biswas, C., Ganguly, D. , Mukherjee, P., Bhattacharya, U. and Hou, Y. (2022) Privacy-aware supervised classification: An informative subspace based multi-objective approach. Pattern Recognition, 122, 108301. (doi: 10.1016/j.patcog.2021.108301)
Biswas, C., Ganguly, D. , Roy, D. and Bhattacharya, U. (2022) Weakly supervised deep metric learning on discrete metric spaces for privacy-preserved clustering. Information Processing and Management, 60(1), 103109. (doi: 10.1016/j.ipm.2022.103109)
2021
Mondal, I., Sen, P. and Ganguly, D. (2021) Multi-Objective Few-shot Learning for Fair Classification. In: 30th ACM International Conference on Information and Knowledge Management (CIKM '21), Queensland, Australia (Virtual Event), 1-5 Nov 2021, pp. 3338-3342. (doi: 10.1145/3459637.3482146)
Pal, D. and Ganguly, D. (2021) Effective Query Formulation in Conversation Contextualization: A Query Specificity-based Approach. In: 7th ACM SIGIR International Conference on the Theory of Information Retrieval (ICTIR 2021), 11 Jul 2021, pp. 177-183. ISBN 9781450386111 (doi: 10.1145/3471158.3472237)
Chandra, M., Ganguly, D. , Mitra, P., Pal, B. and Thomas, J. (2021) NIP-GCN: An Augmented Graph Convolutional Network with Node Interaction Patterns. In: 44th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 21), 11-15 July 2021, pp. 2242-2246. (doi: 10.1145/3404835.3463082)
Articles
Ghosh, M., Mukherjee, S., Ganguly, A., Basuchowdhuri, P., Naskar, S. K. and Ganguly, D. (2024) AlpaPICO: Extraction of PICO frames from clinical trial documents using LLMs. Methods, 226, pp. 78-88. (doi: 10.1016/j.ymeth.2024.04.005) (PMID:38643910)
Datta, S., Ganguly, D. , Mitra, M. and Greene, D. (2023) A relative information gain-based query performance prediction framework with generated query variants. ACM Transactions on Information Systems, 41(2), 38. (doi: 10.1145/3545112)
Sen, P., Ganguly, D. and Jones, G. J.F. (2022) I know what you need: investigating document retrieval effectiveness with partial session contexts. ACM Transactions on Information Systems, 40(3), pp. 1-30. (doi: 10.1145/3488667)
Biswas, C., Ganguly, D. , Mukherjee, P., Bhattacharya, U. and Hou, Y. (2022) Privacy-aware supervised classification: An informative subspace based multi-objective approach. Pattern Recognition, 122, 108301. (doi: 10.1016/j.patcog.2021.108301)
Biswas, C., Ganguly, D. , Roy, D. and Bhattacharya, U. (2022) Weakly supervised deep metric learning on discrete metric spaces for privacy-preserved clustering. Information Processing and Management, 60(1), 103109. (doi: 10.1016/j.ipm.2022.103109)
Book Sections
Adhikary, S., Roy, D., Ganguly, D. , Kumar Guha, S. and Ghosh, K. (2023) LeDA: a system for legal data annotation. In: Sileno, G., Spanakis, J. and van Dijck, G. (eds.) Legal Knowledge and Information Systems. Series: Frontiers in artificial intelligence and applications (379). IOS Press, pp. 370-367. ISBN 9781643684734 (doi: 10.3233/faia230990)
Conference or Workshop Item
Sen, P., Mishra, S., Ganguly, D. and Majumder, P. (2022) A Combination of 'Intra and Inter Collection' Relevance Models for Ad-hoc Retrieval in Precision Medicine. CIRCLE 2022, Toulouse, France, 04-07 Jul 2022.
Conference Proceedings
Sinhababu, N., Parry, A., Ganguly, D. , Samanta, D. and Mitra, P. (2024) Few-shot Pairwise Ranking Prompting: An Effective Non-Parametric Retrieval Model. In: 2024 Conference on Empirical Methods in Natural Language Processing, Miami, Florida, USA, 12–16 November 2024, (Accepted for Publication)
Parry, A., MacAvaney, S. and Ganguly, D. (2024) Top-Down Partitioning for Efficient List-Wise Ranking. In: ReNeuIR'24, Washington, DC, USA, 18 July 2024, (Accepted for Publication)
Parry, A., MacAvaney, S. and Ganguly, D. (2024) Exploiting Positional Bias for Query-Agnostic Generative Content in Search. In: 62nd Annual Meeting of the Association for Computational Linguistics (ACL 2024), Bangkok, Thailand, 11-16 August 2024, (Accepted for Publication)
Santra, P., Ghosh, M., Ganguly, D. , Basuchowdhuri, P. and Naskar, S. K. (2024) "The absence of evidence is not the evidence of absence": Fact Verification via Information Retrieval-based In-Context Learning. In: 26th International Conference on Big Data Analytics and Knowledge Discovery (DAWAK 2024), Naples, Italy, 26-28 August 2024, (Accepted for Publication)
Parry, A., Ganguly, D. and Chandra, M. (2024) In-Context Learning or: How I Learned to Stop Worrying and Love Applied Information Retrieval. In: 47th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2024), Washington D.C., USA, 14-18 Jul 2024, (Accepted for Publication)
Vanneste, J., Verma, M. and Ganguly, D. (2024) Detecting and Explaining Emotions in Video Advertisements. In: 47th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 2024), Washington D.C., USA, 14-18 Jul 2024, (Accepted for Publication)
Santra, P., Ghosh, M., Mukherjee, S., Ganguly, D. , Basuchowdhuri, P. and Naskar, S. K. (2024) Unleashing the Power of Large Language Models: A Hands-On Tutorial. In: 15th Annual Meeting of the Forum for Information Retrieval Evaluation, Panjim, Goa, India, 15-18 Dec 2023, pp. 149-152. ISBN 9798400716324 (doi: 10.1145/3632754.3632943)
Satapara, S., Mehta, P., Modha, S. and Ganguly, D. (2024) Indian Language Summarization at FIRE 2023. In: 15th Annual Meeting of the Forum for Information Retrieval Evaluation, Panjim, Goa, India, 15-18 Dec 2023, pp. 27-29. (doi: 10.1145/3632754.3634662)
Pandian, S., Ganguly, D. and MacAvaney, S. (2023) Evaluating the Explainability of Neural Rankers. In: 46th European Conference on Information Retrieval (ECIR2024), Glasgow, Scotland, 24-28 March 2024, (Accepted for Publication)
Datta, S., Ganguly, D. , MacAvaney, S. and Greene, D. (2023) A Deep Learning Approach for Selective Relevance Feedback. In: 46th European Conference on Information Retrieval (ECIR2024), Glasgow, Scotland, 24-28 March 2024, (Accepted for Publication)
Chandra, M., Ganguly, D. , Saha, T. and Ounis, I. (2023) 'Choose Your Data Wisely’: Active Learning based Selection with Multi-Objective Optimisation for Mitigating Stereotypes. In: 32nd ACM International Conference on Information and Knowledge Management (CIKM 2023), Birmingham, UK, 21-25 Oct 2023, pp. 3768-3772. ISBN 9798400701245 (doi: 10.1145/3583780.3615261)
Ghosh, M., Ganguly, D. , Basuchowdhuri, P. and Kumar Naskar, S. (2023) Extracting Methodology Components from AI Research Papers: A Data-driven Factored Sequence Labeling Approach. In: 32nd ACM International Conference on Information and Knowledge Management (CIKM 2023), Birmingham, UK, 21-25 Oct 2023, pp. 3897-3901. ISBN 9798400701245 (doi: 10.1145/3583780.3615258)
Saha, T., Ganguly, D. , Saha, S. and Mitra, P. (2023) Workshop on Large Language Models' Interpretability and Trustworthiness (LLMIT). In: 32nd ACM International Conference on Information and Knowledge Management (CIKM 2023), Birmingham, UK, 21-25 Oct 2023, pp. 5290-5293. ISBN 9798400701245 (doi: 10.1145/3583780.3615311)
Ganguly, D. and Yilmaz, E. (2023) Query-Specific Variable Depth Pooling via Query Performance Prediction. In: 46th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR23), Taipei, Taiwan, 23-27 July 2023, pp. 2303-2307. ISBN 9781450394086 (doi: 10.1145/3539618.3592046)
Llordes, M., Ganguly, D. , Bhatia, S. and Agarwal, C. (2023) Explain Like I am BM25: Interpreting a Dense Model’s Ranked-List with a Sparse Approximation. In: 46th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR23), Taipei, Taiwan, 23-27 July 2023, pp. 1976-1980. ISBN 9781450394086 (doi: 10.1145/3539618.3591982)
Singh, A., Ganguly, D. , Datta, S. and McDonald, C. (2023) Unsupervised Query Performance Prediction for Neural Models with Pairwise Rank Preferences. In: 46th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR23), Taipei, Taiwan, 23-27 July 2023, pp. 2486-2490. ISBN 9781450394086 (doi: 10.1145/3539618.3592082)
Datta, S., Ganguly, D. , Greene, D. and Mitra, M. (2023) On the Feasibility and Robustness of Pointwise Evaluation of Query Performance Prediction. In: QPP++ 2023: Query Performance Prediction and Its Evaluation in New Tasks, Dublin, Ireland, 06 Apr 2023, pp. 7-12.
Datta, S., Ganguly, D. , Mothe, J. and Ullah, M. Z. (2023) Combining Word Embedding Interactions and LETOR Feature Evidences for Supervised QPP. In: QPP++ 2023: Query Performance Prediction and Its Evaluation in New Tasks, Dublin, Ireland, 06 Apr 2023, pp. 13-19.
Ganguly, D. , Conrad, J. G., Ghosh, K., Ghosh, S., Goyal, P., Bhattacharya, P., Nigam, S. K. and Paul, S. (2023) Legal IR and NLP: The History, Challenges, and State-of-the-Art. In: 45th European Conference on Information Retrieval (ECIR 2023), Dublin, Ireland, 02-06 Apr 2023, pp. 331-340. ISBN 9783031282409 (doi: 10.1007/978-3-031-28241-6_34)
Ganguly, D. , Parker, A. and Aji Mattew, S. (2023) Automatic Videography Generation from Audio Tracks. In: 45th European Conference on Information Retrieval (ECIR'23), Dublin, Ireland, 02-06 Apr 2023, pp. 281-287. ISBN 9783031282409 (doi: 10.1007/978-3-031-28241-6_27)
Jones, G. J.F., Sen, P., Ganguly, D. and Yilmaz, E. (2022) Workshop on Proactive and Agent-Supported Information Retrieval (PASIR). In: CIKM '22: The 31st ACM International Conference on Information and Knowledge Management, Atlanta, GA, US, 17-21 Oct 2022, pp. 5167-5168. ISBN 9781450392365 (doi: 10.1145/3511808.3557939)
Sen, P., Saha, S., Ganguly, D. , Verma, M. and Roy, D. (2022) Measuring and Comparing the Consistency of IR Models for Query Pairs with Similar and Different Information Needs. In: 31st ACM International Conference on Information and Knowledge Management (CIKM '22), Atlanta, Georgia, USA, 17-21 October 2022, pp. 4449-4453. ISBN 9781450392365 (doi: 10.1145/3511808.3557637)
Datta, S., MacAvaney, S. , Ganguly, D. and Greene, D. (2022) A 'Pointwise-Query, Listwise-Document' based Query Performance Prediction Approach. In: SIGIR 2022: 45th International ACM SIGIR Conference on Research and Development in Information Retrieval, Madrid, Spain, 11-15 Jul 2022, pp. 2148-2153. ISBN 9781450387323 (doi: 10.1145/3477495.3531821)
Ganguly, D. , Datta, S., Mitra, M. and Greene, D. (2022) An Analysis of Variations in the Effectiveness of Query Performance Prediction. In: 44th European Conference on Information Retrieval (ECIR 2022), Stavanger, Norway, 10-14 Apr 2022, pp. 215-229. ISBN 9783030997359 (doi: 10.1007/978-3-030-99736-6_15)
Datta, S., Ganguly, D. , Greene, D. and Mitra, M. (2022) Deep-QPP: a Pairwise Interaction-based Deep Learning Model for Supervised Query Performance Prediction. In: WSDM '22: 15th ACM International Conference on Web Search and Data Mining, 21-25 Feb 2022, pp. 201-209. ISBN 9781450391320
Mondal, I., Sen, P. and Ganguly, D. (2021) Multi-Objective Few-shot Learning for Fair Classification. In: 30th ACM International Conference on Information and Knowledge Management (CIKM '21), Queensland, Australia (Virtual Event), 1-5 Nov 2021, pp. 3338-3342. (doi: 10.1145/3459637.3482146)
Pal, D. and Ganguly, D. (2021) Effective Query Formulation in Conversation Contextualization: A Query Specificity-based Approach. In: 7th ACM SIGIR International Conference on the Theory of Information Retrieval (ICTIR 2021), 11 Jul 2021, pp. 177-183. ISBN 9781450386111 (doi: 10.1145/3471158.3472237)
Chandra, M., Ganguly, D. , Mitra, P., Pal, B. and Thomas, J. (2021) NIP-GCN: An Augmented Graph Convolutional Network with Node Interaction Patterns. In: 44th International ACM SIGIR Conference on Research and Development in Information Retrieval (SIGIR 21), 11-15 July 2021, pp. 2242-2246. (doi: 10.1145/3404835.3463082)
Supervision
- Bosman, Isak
Optimizing Natural Language Processing on Edge Devices - Das, Susmita
|Topic: Automated Unit Test Generation using LLMs| Our research would be focused on generating unit test cases using large language models (LLMs). We first plan to generate unit test cases from a given natural language description or code snippet by - Parry, Andrew
Modelling Uncertainties in Neural Networks for Improved Defence against Adversarial Attacks