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The Effects of Time on Query Flow Graph-based Models for Query Suggestion
 

The Effects of Time on Query Flow Graph-based Models for Query Suggestion

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Ranieri Baraglia, Carlos Castillo, Debora Donato, Franco Maria Nardini, Raffaele Perego and Fabrizio Silvestri: "The Effects of Time on Query Flow Graph-based Models for Query Suggestion". In ...

Ranieri Baraglia, Carlos Castillo, Debora Donato, Franco Maria Nardini, Raffaele Perego and Fabrizio Silvestri: "The Effects of Time on Query Flow Graph-based Models for Query Suggestion". In proceedings of RIAO. Paris, France, 2010.

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    The Effects of Time on Query Flow Graph-based Models for Query Suggestion The Effects of Time on Query Flow Graph-based Models for Query Suggestion Presentation Transcript

    • The Effects of Time on Query Flow Graph-based Models for Query Suggestion Carlos Castillo, Debora Donato Ranieri Baraglia, Franco Maria Nardini Raffaele Perego, Fabrizio Silvestri Yahoo! Research Barcelona HPC Lab, ISTI-CNR, Pisa martedì 4 maggio 2010
    • Outline martedì 4 maggio 2010
    • Outline • Introduction • Aims of this Work • The Query-Flow Graph • Evaluating the Aging Effect • Combating the Aging Effect • Distributed QFG Building • Conclusions & Future Works martedì 4 maggio 2010
    • Introduction martedì 4 maggio 2010
    • Introduction • Web search engines use query recommender systems to improve users’ search experience; martedì 4 maggio 2010
    • Introduction • Web search engines use query recommender systems to improve users’ search experience; • Query recommender systems give hints to users on possible “interesting queries”: • relative to their information needs; martedì 4 maggio 2010
    • Introduction • Web search engines use query recommender systems to improve users’ search experience; • Query recommender systems give hints to users on possible “interesting queries”: • relative to their information needs; • Query recommender systems exploit the knowledge of past web search engines users: • recorded in query logs. martedì 4 maggio 2010
    • Aims of this Work martedì 4 maggio 2010
    • Aims of this Work • to show that time has negative effects on a query recommender model: • the model becomes unable to generate good suggestions as time passes; • bursty queries; martedì 4 maggio 2010
    • Aims of this Work • to show that time has negative effects on a query recommender model: • the model becomes unable to generate good suggestions as time passes; • bursty queries; • to extend a state-of-the-art recommender system by providing a methodology for dealing efficiently with evolving data; • to define a “good” strategy to update the model; • to define an distributed/parallel algorithm to update the model; martedì 4 maggio 2010
    • The Query-Flow Graph martedì 4 maggio 2010
    • The Query-Flow Graph • barcelona fc QFG [Boldi et al., CIKM’08] is a website compact and powerful representation 0.043 barcelona fc of Web Search engine users’ behavior; 0.031 fixtures barcelona fc 0.017 real madrid 0.080 0.011 0.506 0.439 barcelona hotels 0.072 0.018 cheap barcelona 0.023 hotels 0.029 <T> barcelona luxury 0.043 barcelona 0.018 barcelona hotels weather 0.416 0.523 0.100 barcelona weather online martedì 4 maggio 2010
    • The Query-Flow Graph • barcelona fc QFG [Boldi et al., CIKM’08] is a website compact and powerful representation 0.043 barcelona fc of Web Search engine users’ behavior; 0.031 fixtures • QFG is a graph composed by: 0.080 barcelona fc 0.017 real madrid 1. a set of nodes, V = Q ∪ {s,t}; 0.011 0.506 0.439 2. a set of directed edges, E ⊆ V x V: barcelona hotels 0.072 0.018 cheap • barcelona 0.023 (q, q’) are connected if they are 0.029 hotels <T> consecutive at least one time in 0.043 barcelona luxury at least one session; barcelona 0.018 barcelona hotels weather 0.416 3. a weighting function w = E --> (0, 1]: • 0.523 assigning a weight w(q, q’) to 0.100 each edge; barcelona weather online martedì 4 maggio 2010
    • The Query-Flow Graph martedì 4 maggio 2010
    • The Query-Flow Graph • two weighting schemes: • relative frequencies: counting query occurrences; • chaining probabilities: (q,q’) in the same chain • classification on a set of features (text, n-grams, session) over all sessions where (q,q’) are consecutive; martedì 4 maggio 2010
    • The Query-Flow Graph • two weighting schemes: • relative frequencies: counting query occurrences; • chaining probabilities: (q,q’) in the same chain • classification on a set of features (text, n-grams, session) over all sessions where (q,q’) are consecutive; • noisy edges: edges with low probability are removed; martedì 4 maggio 2010
    • The Query-Flow Graph martedì 4 maggio 2010
    • The Query-Flow Graph • Query recommendation: • random walk with restart on the graph; • considering history of the users (on the preference vector); martedì 4 maggio 2010
    • The Query-Flow Graph • Query recommendation: • random walk with restart on the graph; • considering history of the users (on the preference vector); • A score is associated to each suggestion; martedì 4 maggio 2010
    • Experimental Framework martedì 4 maggio 2010
    • Experimental Framework • Experiments on the AOL query log: martedì 4 maggio 2010
    • Experimental Framework • Experiments on the AOL query log: • 20 millions queries; martedì 4 maggio 2010
    • Experimental Framework • Experiments on the AOL query log: • 20 millions queries; • 650,000 different users; martedì 4 maggio 2010
    • Experimental Framework • Experiments on the AOL query log: • 20 millions queries; • 650,000 different users; • 3 months (03/01/2006 --> 05/31/2006). martedì 4 maggio 2010
    • Experimental Framework • Experiments on the AOL query log: • 20 millions queries; • 650,000 different users; • 3 months (03/01/2006 --> 05/31/2006). • Three segments of the query log: M1 M2 !"#$%&'()$ !"#$*+',-$ !"#$%&.$ /!#)$%&.$ martedì 4 maggio 2010
    • Experimental Assumptions martedì 4 maggio 2010
    • Boldi et al. in [4]. This method uses chaining probabi measured by means of a machine learning method. The Experimental tial step was thus to extract those features from each t ing log, and storing them into a compressed graph re sentation. In particular we extracted 25 different feat Assumptions (time-related, session and textual features) for each pa queries (q, q ￿ ) that are consecutive in at least one sessio the query log. Table 1 shows the number of nodes and edges of the • M , M are used for training; 1 2 ferent graphs corresponding to each query log segment for training. • two different QFGs; time window March 06 id M1 nodes 3,814,748 edges 6,129,629 April 06 M2 3,832,973 6,266,648 Table 1: Number of nodes and edges for the gra corresponding to the two different training ments. It is important to remark that we have not re-trained classification model for the assignment of weights associ with QFG edges. We reuse the one that has been used i for segmenting users sessions into query chains1 . Th another point in favor of QFG-based models. Once you t the classifier to assign weights to QFG edges, you can r it on different data-sets without losing in effectiveness. martedì 4 maggio 2010 1
    • Boldi et al. in [4]. This method uses chaining probabi measured by means of a machine learning method. The Experimental tial step was thus to extract those features from each t ing log, and storing them into a compressed graph re sentation. In particular we extracted 25 different feat Assumptions (time-related, session and textual features) for each pa queries (q, q ￿ ) that are consecutive in at least one sessio the query log. Table 1 shows the number of nodes and edges of the • M , M are used for training; 1 2 ferent graphs corresponding to each query log segment for training. • two different QFGs; time window March 06 id M1 nodes 3,814,748 edges 6,129,629 April 06 M2 3,832,973 6,266,648 • Queries in the third month Number of nodes testing; for the gra Table 1: are used for and edges corresponding to the two different training ments. It is important to remark that we have not re-trained classification model for the assignment of weights associ with QFG edges. We reuse the one that has been used i for segmenting users sessions into query chains1 . Th another point in favor of QFG-based models. Once you t the classifier to assign weights to QFG edges, you can r it on different data-sets without losing in effectiveness. martedì 4 maggio 2010 1
    • Boldi et al. in [4]. This method uses chaining probabi measured by means of a machine learning method. The Experimental tial step was thus to extract those features from each t ing log, and storing them into a compressed graph re sentation. In particular we extracted 25 different feat Assumptions (time-related, session and textual features) for each pa queries (q, q ￿ ) that are consecutive in at least one sessio the query log. Table 1 shows the number of nodes and edges of the • M , M are used for training; 1 2 ferent graphs corresponding to each query log segment for training. • two different QFGs; time window March 06 id M1 nodes 3,814,748 edges 6,129,629 April 06 M2 3,832,973 6,266,648 • Queries in the third month Number of nodes testing; for the gra Table 1: are used for and edges corresponding to the two different training • We evaluate the aging effect by measuring the quality ments. of suggestions produced by models on M , and M ; It is important to remark that we have not re-trained 1 2 classification model for the assignment of weights associ • If the model ages M with QFG edges. We reuse the one that has been used i outperforms M , in terms of for segmenting users sessions1into query chains1 . Th 2 another point in favor of QFG-based models. Once you t quality of suggestions; the classifier to assign weights to QFG edges, you can r it on different data-sets without losing in effectiveness. martedì 4 maggio 2010 1
    • Evaluating the Aging Effect martedì 4 maggio 2010
    • Evaluating the Aging Effect 1e+06 Top 1000 queries in month 1 on month 1 Top 1000 queries in month 3 on month 1 100000 10000 1000 100 10 !"#"$%"&'()"*+",' 1 1 10 100 1000 martedì 4 maggio 2010
    • Evaluating the Aging Effect • Two classes of test queries: • F1: 30 queries highly 1e+06 Top 1000 queries in month 1 on month 1 Top 1000 queries in month 3 on month 1 frequent in M1 having a 100000 large drop in the test month (ex. shakira). 10000 • F3: 30 queries highly 1000 frequent in the test month having a large 100 drop in M1 (ex. da vinci 10 !"#"$%"&'()"*+",' code, mothers day gift); 1 1 10 100 1000 martedì 4 maggio 2010
    • Evaluating the Aging Effect • Two classes of test queries: • F1: 30 queries highly 1e+06 Top 1000 queries in month 1 on month 1 Top 1000 queries in month 3 on month 1 frequent in M1 having a 100000 large drop in the test month (ex. shakira). 10000 • F3: 30 queries highly 1000 frequent in the test month having a large 100 drop in M1 (ex. da vinci 10 !"#"$%"&'()"*+",' code, mothers day gift); • 1 F1, F3 contain very diverse 1 10 100 1000 queries; martedì 4 maggio 2010
    • Evaluating the Aging Effect (II) martedì 4 maggio 2010
    • 3742 2652 2162 2615 Evaluating the Aging 2001 2341 1913 2341 1913 2341 Effect (II) (!!!" '!!!" &!!!" %!!!" )*+," -./)01"2.342+*5" $!!!" #!!!" !" #" $" %" &" '" (" martedì 4 maggio 2010
    • 3742 2652 2162 2615 Evaluating the Aging 2001 2341 1913 2341 1913 2341 Effect (II) • When k suggestions share the same score, those are useless; (!!!" '!!!" &!!!" %!!!" )*+," -./)01"2.342+*5" $!!!" #!!!" !" #" $" %" &" '" (" martedì 4 maggio 2010
    • 3742 2652 2162 2615 Evaluating the Aging 2001 2341 1913 2341 1913 2341 Effect (II) • When k suggestions share the same score, those are useless; (!!!" • Same suggestion score: '!!!" • &!!!" same probability on the graph; %!!!" )*+," -./)01"2.342+*5" • the model is not able to $!!!" give a priority to #!!!" recommendations; !" #" $" %" &" '" (" martedì 4 maggio 2010
    • 3742 2652 2162 2615 Evaluating the Aging 2001 2341 1913 2341 1913 2341 Effect (II) • When k suggestions share the same score, those are useless; (!!!" • Same suggestion score: '!!!" • &!!!" same probability on the graph; %!!!" )*+," -./)01"2.342+*5" • the model is not able to $!!!" give a priority to #!!!" recommendations; !" • Confirmed by an user-study #" $" %" &" '" (" on F1, and F3; martedì 4 maggio 2010
    • Evaluating the Aging Effect (III) martedì 4 maggio 2010
    • Evaluating the Aging Effect (III) • Working hypothesis: • useful recommendations do not share the same recommendation score; martedì 4 maggio 2010
    • Evaluating the Aging Effect (III) • Working hypothesis: • useful recommendations do not share the same recommendation score; • Automatic evaluation; • 400 highly frequent queries in the test month; • evaluating the number of useful recommendations; • k = 3; martedì 4 maggio 2010
    • Evaluating the Aging Effect (IV) martedì 4 maggio 2010
    • ate recommendations are taken from different query Evaluating the Aging recommendations with their assigned relative scores. Effect (IV) reduces the “noise” on the data and generates more precise knowledge on which recommendations are computed. Fur- thermore, the increase is quite independent from the thresh- old level, i.e. by increasing the threshold from 0.5 to 0.75 the overall quality is, roughly, constant. • Results: filtering threshold average number of useful sugges- tions on M1 average number of useful sugges- tions on M2 0 2.84 2.91 0.5 5.85 6.23 0.65 5.85 6.23 0.75 5.85 6.18 Table 4: Recommendation statistics obtained by us- ing the automatic evaluation method on a set of 400 queries drawn from the most frequent in the third month. We further break down the overall results shown in Table 4 to show the number of queries on which the QFG-based martedì 4 maggio 2010
    • ate recommendations are taken from different query Evaluating the Aging recommendations with their assigned relative scores. Effect (IV) reduces the “noise” on the data and generates more precise knowledge on which recommendations are computed. Fur- thermore, the increase is quite independent from the thresh- old level, i.e. by increasing the threshold from 0.5 to 0.75 the overall quality is, roughly, constant. • Results: filtering threshold average number of useful sugges- tions on M1 average number of useful sugges- tions on M2 0 2.84 2.91 0.5 5.85 6.23 0.65 5.85 6.23 0.75 5.85 6.18 • Table 4: Recommendation statistics obtained by us- Average ing the automatic evaluation method on a set of 400 number of useful suggestions is greater in M2 than queries drawn from the most frequent in the third in M1; month. • Filtering process helps a lot; We further break down the overall results shown in Table 4 to show the number of queries on which the QFG-based martedì 4 maggio 2010
    • Evaluating the Aging Effect (V) martedì 4 maggio 2010
    • Evaluating the Aging Effect (V) • On a histogram (cumulative distribution): 400 300 200 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 >18 M1 M2 martedì 4 maggio 2010
    • Evaluating the Aging Effect (V) • On a histogram (cumulative distribution): 400 300 200 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 >18 M1 M2 • Results on M are always better than those on M : 2 1 • less queries without suggestions; martedì 4 maggio 2010
    • Combating the Aging Effect martedì 4 maggio 2010
    • Combating the Aging Effect • QFG recommender models age: • Average recommendation quality degrades; • Recommendations should not be influenced by time; martedì 4 maggio 2010
    • Combating the Aging Effect • QFG recommender models age: • Average recommendation quality degrades; • Recommendations should not be influenced by time; • Update of the model vs. rebuilding it “from scratch”; martedì 4 maggio 2010
    • Combating the Aging Effect (II) martedì 4 maggio 2010
    • Combating the Aging t a model or which Effect (II) QFGs. Suppose the model used to generate recommenda- tions consists of a portion of data representing one month (for M1 and M2 ) or two months (for M12 ) of the query commen- log. The model is being updated every 15 days (for M1 • to always and M2 ) or every 30 days (for M12 ). By using the first ap- Solution: incremental update of Mevery means days to rebuild proach, we pay 22 (44) minutes 1 by 15 (30) of “fresh data” in M2 • the new model from scratch on a new set of data obtained Graph the last two months of the query log. Instead, by using from algebra [Bordino et al., 2008]; FLOW • the second approach, we need to pay only 15 (32) minutes Some measures on the two different approaches: for updating the one-month (two-months) QFG. apidly in “From scratch” “Incremental” commen- Dataset strategy [min.] strategy [min.] endation M1 (March 2006) 21 14 tive queries. M2 (April 2006) 22 15 both fre- M12 (March and April) 44 32 heir value ariation). Table 5: Time needed to build a Query Flow Graph o movies, from scratch and using our “incremental” approach eral with (from merging two QFG representing an half of it is easy data). martedì 4 maggio 2010
    • Combating the Aging t a model or which Effect (II) QFGs. Suppose the model used to generate recommenda- tions consists of a portion of data representing one month (for M1 and M2 ) or two months (for M12 ) of the query commen- log. The model is being updated every 15 days (for M1 • to always and M2 ) or every 30 days (for M12 ). By using the first ap- Solution: incremental update of Mevery means days to rebuild proach, we pay 22 (44) minutes 1 by 15 (30) of “fresh data” in M2 • the new model from scratch on a new set of data obtained Graph the last two months of the query log. Instead, by using from algebra [Bordino et al., 2008]; FLOW • the second approach, we need to pay only 15 (32) minutes Some measures on the two different approaches: for updating the one-month (two-months) QFG. apidly in “From scratch” “Incremental” commen- Dataset strategy [min.] strategy [min.] endation M1 (March 2006) 21 14 tive queries. M2 (April 2006) 22 15 both fre- M12 (March and April) 44 32 • heir value Incremental updates: 2/3 of the build w.r.t. “from scratch” strategy; ariation). Table 5: Time needed to time a Query Flow Graph from scratch and using our “incremental” approach • o movies, Evaluation onmerging two QFG representing an half of eral with (from the same set of 400 queries; it is easy data). martedì 4 maggio 2010
    • Combating the Aging Effect (III) martedì 4 maggio 2010
    • 3698 shakira video shakira 3135 shakira nude Combating the Aging 3099 shakira wallpaper 3020 shakira biography 3018 shakira aol music 2015 free video downloads Effect (III) Table 7: Some examples of recommendations gen- erated on different QFG models. Queries used to generate recommendations are taken from different query sets. • Results: filtering threshold average number of useful sugges- tions on M2 average number of useful sugges- tions on M12 0 2.91 3.64 0.5 6.23 7.95 0.65 6.23 7.94 0.75 6.18 7.9 Table 8: Recommendation statistics obtained by us- ing the automatic evaluation method on a relatively large set of 400 queries drawn from the most fre- quent in the third month. martedì 4 maggio 2010 gated the main reasons why we obtain such an improvement.
    • 3698 shakira video shakira 3135 shakira nude Combating the Aging 3099 shakira wallpaper 3020 shakira biography 3018 shakira aol music 2015 free video downloads Effect (III) Table 7: Some examples of recommendations gen- erated on different QFG models. Queries used to generate recommendations are taken from different query sets. • Results: filtering threshold average number of useful sugges- tions on M2 average number of useful sugges- tions on M12 0 2.91 3.64 0.5 6.23 7.95 0.65 6.23 7.94 0.75 6.18 7.9 • Average number of useful suggestion is obtained by us- Table 8: Recommendation statistics greater in ing the automatic evaluation method on a relatively M12 than in M2, or 400M1; large set of in queries drawn from the most fre- quent in the third month. martedì 4 maggio 2010 gated the main reasons why we obtain such an improvement.
    • Combating the Aging Effect (IV) martedì 4 maggio 2010
    • 12,5 Combating the Aging 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 >18 M1 M2 M12 Effect (IV) Figure 4: Histogram showing the number of queries (on the y axis) having a certain number of useful recommendations (on the x axis). Results are eval- • uated automatically. On a histogram (cumulative distribution): 400 300 t 200 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 >18 M1 M2 M12 - Figure 5: Histogram showing the total number of queries (on the y axis) having at least a certain num- ber of useful recommendations (on the x axis). For instance the third bucket shows how many queries martedì 4 maggio 2010
    • 12,5 Combating the Aging 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 >18 M1 M2 M12 Effect (IV) Figure 4: Histogram showing the number of queries (on the y axis) having a certain number of useful recommendations (on the x axis). Results are eval- • uated automatically. On a histogram (cumulative distribution): 400 300 t 200 100 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 >18 M1 M2 M12 - • Results on M12 are always better than M1, and M2; Figure 5: Histogram showing the total number of • queries improvement ofhaving at least aleast four good large (on the y axis) queries with at certain num- suggestions; ber of useful recommendations (on the x axis). For instance the third bucket shows how many queries martedì 4 maggio 2010
    • Distributed QFG Building martedì 4 maggio 2010
    • Distributed QFG 4. using the graph algebra described in [8], each pa graph is iteratively merged. Each iteration is do parallel on the different available nodes of the clo Building 5. the final resulting data-graph is now processed other steps [4] (normalization, chain extraction, dom walk) to obtain the complete and usable QF • a parallel way to update QFGs: 01)2()*+,'#3456&#7)8# Divide-and-Conquer approach; • the query log is split in m !"#$%&'# !"#$%&'# !"#$%&'# !"#$%&'# parts; • parallel extraction of the -./# -./# -./# -./# features; • compressing step; !#()*+,#-./# !#()*+,#-./# • merging graphs; • final operations 9#()*+,'#-./# (normalization, pagerank, etc.); martedì 4 maggio 2010 Figure 6: Example of the building of a two mo
    • Conclusions martedì 4 maggio 2010
    • Conclusions • We study the effects of time on QFG-based query recommender systems; martedì 4 maggio 2010
    • Conclusions • We study the effects of time on QFG-based query recommender systems; • We built different QFGs from the AOL query log; • we analyze the quality of recommendation; • we show that recommendation models ages; • we introduce an “incremental” algorithm for updating the model; • we propose a parallel/distributed way of building QFGs; martedì 4 maggio 2010
    • Future Works martedì 4 maggio 2010
    • Future Works • to define a strategy for merging graphs assigning different weights to each subgraph; • more importance to “fresh” data; martedì 4 maggio 2010
    • Future Works • to define a strategy for merging graphs assigning different weights to each subgraph; • more importance to “fresh” data; • to compare the robustness of QFG recommender systems with other query recommenders with respect to aging; martedì 4 maggio 2010
    • Future Works • to define a strategy for merging graphs assigning different weights to each subgraph; • more importance to “fresh” data; • to compare the robustness of QFG recommender systems with other query recommenders with respect to aging; • to design a MapReduce algorithm to build and update efficiently QFGs recommender systems; martedì 4 maggio 2010
    • Questions? Thank you for your attention! martedì 4 maggio 2010
    • References • [Boldi et al., CIKM’08]: The Query Flow Graph: model and applications. Boldi, Bonchi, Castillo, Donato, Gionis,Vigna. CIKM’08. • [Boldi et al., WSCD’09]: Query Suggestions using Query-Flow Graphs. Boldi, Bonchi, Castillo, Donato, Vigna. WSCD’09. • [Bordino et al., 2008]: Algebra for the joint mining of query log graphs, 2008. martedì 4 maggio 2010