Valentino Di Donato | Roma Tre University, Rome, Italy (original) (raw)

Papers by Valentino Di Donato

Springer eBooks, 2018

We introduce a hybrid metaphor for the visualization of the reconciliations of co-phylogenetic tr... more We introduce a hybrid metaphor for the visualization of the reconciliations of co-phylogenetic trees, that are mappings among the nodes of two trees. The typical application is the visualization of the co-evolution of hosts and parasites in biology. Our strategy combines a space-filling and a node-link approach. Differently from traditional methods, it guarantees an unambiguous and 'downward' representation whenever the reconciliation is time-consistent (i.e., meaningful). We address the problem of the minimization of the number of crossings in the representation, by giving a characterization of planar instances and by establishing the complexity of the problem. Finally, we propose heuristics for computing representations with few crossings.

IEEE ACM Transactions on Networking, Jun 1, 2019

With the increasing diffusion of Internet probing technologies, a large amount of regularly colle... more With the increasing diffusion of Internet probing technologies, a large amount of regularly collected traceroutes are available for Internet Service Providers (ISPs) at low cost. We show how it is possible, given solely an arbitrary set of traceroutes, to spot routing paths that change similarly over time and aggregate them into inferred routing events. With respect to previous works, our approach does not require any knowledge of the network, does not need complex integration of several data sources, and exploits the asynchronicity of measurements to accurately position events in time. The formal model at the basis of our methodology revolves around the notion of empathy, a relation that binds similarly behaving traceroutes. The correctness and completeness of our approach are based on structural properties that are easily expressed in terms of empathic measurements. We perform experiments with data from public measurement infrastructures like RIPE Atlas, showing the effectiveness of our algorithm in distilling significant events from a large amount of traceroute data. We also validate the accuracy of the inferred events against ground-truth knowledge of routing changes originating from induced and spontaneous routing events. Given these promising results, we believe our methodology can be an effective aid for troubleshooting at the ISPs level. The source code of our algorithm is publicly available at .

arXiv (Cornell University), Dec 12, 2014

With the increasing diffusion of Internet probing technologies, a large amount of regularly colle... more With the increasing diffusion of Internet probing technologies, a large amount of regularly collected traceroutes are available for Internet Service Providers (ISPs) at low cost. We introduce a practically applicable methodology and algorithm that, given solely an arbitrary set of traceroutes, spot routing paths that change similarly over time, aggregate them into inferred events, and report each event along with the impacted observation points and a small set of IP addresses that can help identify its cause. The formal model at the basis of our methodology revolves around the notion of empathy, a relation that binds similarly behaving traceroutes. The correctness and completeness of our approach are based on structural properties that are easily expressed in terms of empathic measurements. We perform experiments with data from public measurement infrastructures like RIPE Atlas, showing the effectiveness of our algorithm in distilling events from a large amount of traceroute data. We also validate the accuracy of the inferred events against ground-truth knowledge of routing changes originating from induced and spontaneous routing events. Given these promising results, we believe our methodology can be an effective aid for ISPs to detect and track routing changes affecting many users (with potentially adverse effects on their connection quality).

arXiv (Cornell University), Sep 2, 2015

We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining th... more We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining the readability features of orthogonal drawings with the expressive power of matrix representations. In an L-drawing, vertices have exclusive xand y-coordinates and edges consist of two segments, one exiting the source vertically and one entering the destination horizontally. We study the problem of computing L-drawings using minimum ink. We prove its NP-completeness and provide a heuristics based on a polynomial-time algorithm that adds a vertex to a drawing using the minimum additional ink. We performed an experimental analysis of the heuristics which confirms its effectiveness.

arXiv (Cornell University), Sep 2, 2015

We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining th... more We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining the readability features of orthogonal drawings with the expressive power of matrix representations. In an L-drawing, vertices have exclusive xand y-coordinates and edges consist of two segments, one exiting the source vertically and one entering the destination horizontally. We study the problem of computing L-drawings using minimum ink. We prove its NP-completeness and provide a heuristics based on a polynomial-time algorithm that adds a vertex to a drawing using the minimum additional ink. We performed an experimental analysis of the heuristics which confirms its effectiveness.

Symposium on Discrete Algorithms, Jan 10, 2016

Given a planar graph G(V, E) and a partition of the neighbors of each vertex v ∈ V in four sets v... more Given a planar graph G(V, E) and a partition of the neighbors of each vertex v ∈ V in four sets v, v, v, and v, the problem WINDROSE PLANARITY asks to decide whether G admits a windrose-planar drawing, that is, a planar drawing in which (i) each neighbor u ∈ v is above and to the right of v, (ii) each neighbor u ∈ v is above and to the left of v, (iii) each neighbor u ∈ v is below and to the left of v, (iv) each neighbor u ∈ v is below and to the right of v, and (v) edges are represented by curves that are monotone with respect to each axis. By exploiting both the horizontal and the vertical relationship among vertices, windrose-planar drawings allow to simultaneously visualize two partial orders defined by means of the edges of the graph. Although the problem is N P-hard in the general case, we give a polynomial-time algorithm for testing whether there exists a windrose-planar drawing that respects a combinatorial embedding that is given as part of the input. This algorithm is based on a characterization of the plane triangulations admitting a windrose-planar drawing. Furthermore, for any embedded graph admitting a windrose-planar drawing we show how to construct one with at most one bend per edge on an O(n) × O(n) grid. The latter result contrasts with the fact that straight-line windrose-planar drawings may require exponential area.

Proceedings of the 13th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications, 2018

We present FLOWMATRIX, a system for the interactive exploration of time-labeled multivariate flow... more We present FLOWMATRIX, a system for the interactive exploration of time-labeled multivariate flows between pairs of geographic locations. FLOWMATRIX offers a coordinated visualization based on the interplay between a geographic map and a matrix that allow to discover trends tied to specific locations while offering an overview of metrics of the flows between all pairs of locations. The input data is clustered following a geographic hierarchy and the user can navigate between different levels of detail. The design of our system privileges the execution of simple tasks like assessing the volume and features of the flows between pairs of locations, enumerating destinations with poor performance, and sorting flow streams based on their volume.

Over the past few years a persistent growth of the number of daily Bitcoin transactions has been ... more Over the past few years a persistent growth of the number of daily Bitcoin transactions has been observed. This trend however, is known to be influenced by a number of phenomena that generate long transaction chains that are not related to real purchases (e.g. wallets shuffling and coin mixing). For a transaction chain we call transaction chain frequency the number of transactions of the chain divided by the time interval of the chain. In this paper, we first analyze to which extent Bitcoin transactions are involved in high frequency transaction chains, in the short and in the long term. Based on this analysis, we then argue that a large fraction of transactions do not refer to explicit human activity, namely to transactions between users that trade goods or services. Finally, we show that most of the transactions are involved into chains whose frequency is roughly stable over time and that we call Bitcoin Heartbeat.

ACM Transactions on Algorithms

Given a planar graph G and a partition of the neighbors of each vertex v in four sets v, v, v, an... more Given a planar graph G and a partition of the neighbors of each vertex v in four sets v, v, v, and v, the problem Windrose Planarity asks to decide whether G admits a windrose-planar drawing, that is, a planar drawing in which (i) each neighbor u ∈ v is above and to the right of v, (ii) each neighbor u ∈ v is above and to the left of v, (iii) each neighbor u ∈ v is below and to the left of v, (iv) each neighbor u ∈ v is below and to the right of v, and (v) edges are represented by curves that are monotone with respect to each axis. By exploiting both the horizontal and the vertical relationship among vertices, windrose-planar drawings allow to simultaneously visualize two partial orders defined by means of the edges of the graph. Although the problem is N P-hard in the general case, we give a polynomial-time algorithm for testing whether there exists a windrose-planar drawing that respects a given combinatorial embedding. This algorithm is based on a characterization of the plane triangulations admitting a windrose-planar drawing. Furthermore, for any embedded graph with n vertices that has a windrose-planar drawing, we can construct one with at most one bend per edge and with at most 2n − 5 bends in total, which lies on the 3n × 3n grid. The latter result contrasts with the fact that straight-line windrose-planar drawings may require exponential area.

International Journal of Foundations of Computer Science

We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining th... more We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining the readability features of orthogonal drawings with the expressive power of adjacency matrix representations. In an L-drawing, vertices have exclusive [Formula: see text]- and [Formula: see text]-coordinates and edges consist of two segments, one exiting the source vertically and one entering the destination horizontally. We study the problem of computing L-drawings using minimum ink. We prove its NP-hardness and provide a heuristic based on a polynomial-time algorithm that adds a vertex to a drawing using the minimum additional ink. We performed an experimental analysis of the heuristic which confirms its effectiveness.

IEEE/ACM Transactions on Networking

NOMS 2016 - 2016 IEEE/IFIP Network Operations and Management Symposium, 2016

Proceedings of the International Working Conference on Advanced Visual Interfaces - AVI '16, 2016

Theoretical Computer Science

We introduce a hybrid metaphor for the visualization of the reconciliations of co-phylogenetic tr... more We introduce a hybrid metaphor for the visualization of the reconciliations of co-phylogenetic trees, that are mappings among the nodes of two trees. The typical application is the visualization of the co-evolution of hosts and parasites in biology. Our strategy combines a space-filling and a node-link approach. Differently from traditional methods, it guarantees an unambiguous and 'downward' representation whenever the reconciliation is time-consistent (i.e., meaningful). We address the problem of the minimization of the number of crossings in the representation, by giving a characterization of planar instances and by establishing the complexity of the problem. Finally, we propose heuristics for computing representations with few crossings.

2015 IEEE Symposium on Computers and Communication (ISCC), 2015

Lecture Notes in Computer Science, 2016

Proceedings of the Twenty-Seventh Annual ACM-SIAM Symposium on Discrete Algorithms, 2015

In the never-ending quest for tools that enable an ISP to smooth troubleshooting and improve awar... more In the never-ending quest for tools that enable an ISP to smooth troubleshooting and improve awareness of network behavior, very much effort has been devoted in the collection of data by active and passive measurement at the data plane and at the control plane level. Exploitation of collected data has been mostly focused on anomaly detection and on root-cause analysis. Our objective is somewhat in the middle. We consider traceroutes collected by a network of probes and aim at introducing a practically applicable methodology to quickly spot measurements that are related to high-impact events happened in the network. Such filtering process eases further in- depth human-based analysis, for example with visual tools which are effective only when handling a limited amount of data. We introduce the empathy relation between traceroutes as the cornerstone of our formal characterization of the traceroutes related to a network event. Based on this model, we describe an algorithm that finds traceroutes related to high-impact events in an arbitrary set of measurements. Evidence of the effectiveness of our approach is given by experimental results produced on real-world data.

2015 IEEE Symposium on Visualization for Cyber Security (VizSec), 2015

Springer eBooks, 2018

We introduce a hybrid metaphor for the visualization of the reconciliations of co-phylogenetic tr... more We introduce a hybrid metaphor for the visualization of the reconciliations of co-phylogenetic trees, that are mappings among the nodes of two trees. The typical application is the visualization of the co-evolution of hosts and parasites in biology. Our strategy combines a space-filling and a node-link approach. Differently from traditional methods, it guarantees an unambiguous and 'downward' representation whenever the reconciliation is time-consistent (i.e., meaningful). We address the problem of the minimization of the number of crossings in the representation, by giving a characterization of planar instances and by establishing the complexity of the problem. Finally, we propose heuristics for computing representations with few crossings.

IEEE ACM Transactions on Networking, Jun 1, 2019

With the increasing diffusion of Internet probing technologies, a large amount of regularly colle... more With the increasing diffusion of Internet probing technologies, a large amount of regularly collected traceroutes are available for Internet Service Providers (ISPs) at low cost. We show how it is possible, given solely an arbitrary set of traceroutes, to spot routing paths that change similarly over time and aggregate them into inferred routing events. With respect to previous works, our approach does not require any knowledge of the network, does not need complex integration of several data sources, and exploits the asynchronicity of measurements to accurately position events in time. The formal model at the basis of our methodology revolves around the notion of empathy, a relation that binds similarly behaving traceroutes. The correctness and completeness of our approach are based on structural properties that are easily expressed in terms of empathic measurements. We perform experiments with data from public measurement infrastructures like RIPE Atlas, showing the effectiveness of our algorithm in distilling significant events from a large amount of traceroute data. We also validate the accuracy of the inferred events against ground-truth knowledge of routing changes originating from induced and spontaneous routing events. Given these promising results, we believe our methodology can be an effective aid for troubleshooting at the ISPs level. The source code of our algorithm is publicly available at .

arXiv (Cornell University), Dec 12, 2014

With the increasing diffusion of Internet probing technologies, a large amount of regularly colle... more With the increasing diffusion of Internet probing technologies, a large amount of regularly collected traceroutes are available for Internet Service Providers (ISPs) at low cost. We introduce a practically applicable methodology and algorithm that, given solely an arbitrary set of traceroutes, spot routing paths that change similarly over time, aggregate them into inferred events, and report each event along with the impacted observation points and a small set of IP addresses that can help identify its cause. The formal model at the basis of our methodology revolves around the notion of empathy, a relation that binds similarly behaving traceroutes. The correctness and completeness of our approach are based on structural properties that are easily expressed in terms of empathic measurements. We perform experiments with data from public measurement infrastructures like RIPE Atlas, showing the effectiveness of our algorithm in distilling events from a large amount of traceroute data. We also validate the accuracy of the inferred events against ground-truth knowledge of routing changes originating from induced and spontaneous routing events. Given these promising results, we believe our methodology can be an effective aid for ISPs to detect and track routing changes affecting many users (with potentially adverse effects on their connection quality).

arXiv (Cornell University), Sep 2, 2015

We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining th... more We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining the readability features of orthogonal drawings with the expressive power of matrix representations. In an L-drawing, vertices have exclusive xand y-coordinates and edges consist of two segments, one exiting the source vertically and one entering the destination horizontally. We study the problem of computing L-drawings using minimum ink. We prove its NP-completeness and provide a heuristics based on a polynomial-time algorithm that adds a vertex to a drawing using the minimum additional ink. We performed an experimental analysis of the heuristics which confirms its effectiveness.

arXiv (Cornell University), Sep 2, 2015

We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining th... more We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining the readability features of orthogonal drawings with the expressive power of matrix representations. In an L-drawing, vertices have exclusive xand y-coordinates and edges consist of two segments, one exiting the source vertically and one entering the destination horizontally. We study the problem of computing L-drawings using minimum ink. We prove its NP-completeness and provide a heuristics based on a polynomial-time algorithm that adds a vertex to a drawing using the minimum additional ink. We performed an experimental analysis of the heuristics which confirms its effectiveness.

Symposium on Discrete Algorithms, Jan 10, 2016

Given a planar graph G(V, E) and a partition of the neighbors of each vertex v ∈ V in four sets v... more Given a planar graph G(V, E) and a partition of the neighbors of each vertex v ∈ V in four sets v, v, v, and v, the problem WINDROSE PLANARITY asks to decide whether G admits a windrose-planar drawing, that is, a planar drawing in which (i) each neighbor u ∈ v is above and to the right of v, (ii) each neighbor u ∈ v is above and to the left of v, (iii) each neighbor u ∈ v is below and to the left of v, (iv) each neighbor u ∈ v is below and to the right of v, and (v) edges are represented by curves that are monotone with respect to each axis. By exploiting both the horizontal and the vertical relationship among vertices, windrose-planar drawings allow to simultaneously visualize two partial orders defined by means of the edges of the graph. Although the problem is N P-hard in the general case, we give a polynomial-time algorithm for testing whether there exists a windrose-planar drawing that respects a combinatorial embedding that is given as part of the input. This algorithm is based on a characterization of the plane triangulations admitting a windrose-planar drawing. Furthermore, for any embedded graph admitting a windrose-planar drawing we show how to construct one with at most one bend per edge on an O(n) × O(n) grid. The latter result contrasts with the fact that straight-line windrose-planar drawings may require exponential area.

Proceedings of the 13th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications, 2018

We present FLOWMATRIX, a system for the interactive exploration of time-labeled multivariate flow... more We present FLOWMATRIX, a system for the interactive exploration of time-labeled multivariate flows between pairs of geographic locations. FLOWMATRIX offers a coordinated visualization based on the interplay between a geographic map and a matrix that allow to discover trends tied to specific locations while offering an overview of metrics of the flows between all pairs of locations. The input data is clustered following a geographic hierarchy and the user can navigate between different levels of detail. The design of our system privileges the execution of simple tasks like assessing the volume and features of the flows between pairs of locations, enumerating destinations with poor performance, and sorting flow streams based on their volume.

Over the past few years a persistent growth of the number of daily Bitcoin transactions has been ... more Over the past few years a persistent growth of the number of daily Bitcoin transactions has been observed. This trend however, is known to be influenced by a number of phenomena that generate long transaction chains that are not related to real purchases (e.g. wallets shuffling and coin mixing). For a transaction chain we call transaction chain frequency the number of transactions of the chain divided by the time interval of the chain. In this paper, we first analyze to which extent Bitcoin transactions are involved in high frequency transaction chains, in the short and in the long term. Based on this analysis, we then argue that a large fraction of transactions do not refer to explicit human activity, namely to transactions between users that trade goods or services. Finally, we show that most of the transactions are involved into chains whose frequency is roughly stable over time and that we call Bitcoin Heartbeat.

ACM Transactions on Algorithms

Given a planar graph G and a partition of the neighbors of each vertex v in four sets v, v, v, an... more Given a planar graph G and a partition of the neighbors of each vertex v in four sets v, v, v, and v, the problem Windrose Planarity asks to decide whether G admits a windrose-planar drawing, that is, a planar drawing in which (i) each neighbor u ∈ v is above and to the right of v, (ii) each neighbor u ∈ v is above and to the left of v, (iii) each neighbor u ∈ v is below and to the left of v, (iv) each neighbor u ∈ v is below and to the right of v, and (v) edges are represented by curves that are monotone with respect to each axis. By exploiting both the horizontal and the vertical relationship among vertices, windrose-planar drawings allow to simultaneously visualize two partial orders defined by means of the edges of the graph. Although the problem is N P-hard in the general case, we give a polynomial-time algorithm for testing whether there exists a windrose-planar drawing that respects a given combinatorial embedding. This algorithm is based on a characterization of the plane triangulations admitting a windrose-planar drawing. Furthermore, for any embedded graph with n vertices that has a windrose-planar drawing, we can construct one with at most one bend per edge and with at most 2n − 5 bends in total, which lies on the 3n × 3n grid. The latter result contrasts with the fact that straight-line windrose-planar drawings may require exponential area.

International Journal of Foundations of Computer Science

We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining th... more We introduce L-drawings, a novel paradigm for representing directed graphs aiming at combining the readability features of orthogonal drawings with the expressive power of adjacency matrix representations. In an L-drawing, vertices have exclusive [Formula: see text]- and [Formula: see text]-coordinates and edges consist of two segments, one exiting the source vertically and one entering the destination horizontally. We study the problem of computing L-drawings using minimum ink. We prove its NP-hardness and provide a heuristic based on a polynomial-time algorithm that adds a vertex to a drawing using the minimum additional ink. We performed an experimental analysis of the heuristic which confirms its effectiveness.

IEEE/ACM Transactions on Networking

NOMS 2016 - 2016 IEEE/IFIP Network Operations and Management Symposium, 2016

Proceedings of the International Working Conference on Advanced Visual Interfaces - AVI '16, 2016

Theoretical Computer Science

We introduce a hybrid metaphor for the visualization of the reconciliations of co-phylogenetic tr... more We introduce a hybrid metaphor for the visualization of the reconciliations of co-phylogenetic trees, that are mappings among the nodes of two trees. The typical application is the visualization of the co-evolution of hosts and parasites in biology. Our strategy combines a space-filling and a node-link approach. Differently from traditional methods, it guarantees an unambiguous and 'downward' representation whenever the reconciliation is time-consistent (i.e., meaningful). We address the problem of the minimization of the number of crossings in the representation, by giving a characterization of planar instances and by establishing the complexity of the problem. Finally, we propose heuristics for computing representations with few crossings.

2015 IEEE Symposium on Computers and Communication (ISCC), 2015

Lecture Notes in Computer Science, 2016

Proceedings of the Twenty-Seventh Annual ACM-SIAM Symposium on Discrete Algorithms, 2015

In the never-ending quest for tools that enable an ISP to smooth troubleshooting and improve awar... more In the never-ending quest for tools that enable an ISP to smooth troubleshooting and improve awareness of network behavior, very much effort has been devoted in the collection of data by active and passive measurement at the data plane and at the control plane level. Exploitation of collected data has been mostly focused on anomaly detection and on root-cause analysis. Our objective is somewhat in the middle. We consider traceroutes collected by a network of probes and aim at introducing a practically applicable methodology to quickly spot measurements that are related to high-impact events happened in the network. Such filtering process eases further in- depth human-based analysis, for example with visual tools which are effective only when handling a limited amount of data. We introduce the empathy relation between traceroutes as the cornerstone of our formal characterization of the traceroutes related to a network event. Based on this model, we describe an algorithm that finds traceroutes related to high-impact events in an arbitrary set of measurements. Evidence of the effectiveness of our approach is given by experimental results produced on real-world data.

2015 IEEE Symposium on Visualization for Cyber Security (VizSec), 2015