CONVEX enables any standalone KB-QA system to answer conversations Look before you Hop: Conversational Question Answering over Knowledge Graphs Using Judicious Context Expansion Philipp Christmann, Rishiraj Saha Roy, Abdalghani Abujabal, Jyotsna Singh, and Gerhard Weikum Max Planck Institute for Informatics, Germany Contact: pchristm @mmci.uni-saarland.de Data and Code: qa.mpi-inf.mpg.de/convex MOTIVATION ★ Users issue series of questions on specific topic ★ In a natural interaction setting, follow-up questions are incomplete with information intentionally left out ★ State-of-the-art KG-QA can not handle incomplete questions without cue words APPROACH ★ First question establishes a conversation context ★ Context is expanded judiciously by turns ★ Frontier nodes define the expansion border ★ Question relevance, context relevance and KG priors are important signals in frontier node determination ★ Answer is in close proximity to frontier nodes ★ CONVEX is completely unsupervised and can enable any KG-QA system to handle ad-hoc conversations An illustration of the ambiguity in frontier node selection and how context relevance can help. Books Movies Soccer Music TV Series When was the first book of the book series The Dwarves published? Who played the joker in The Dark Knight? Which European team did Diego Costa represent in the year 2018? Led Zeppelin had how many band members? Who is the actor of James Gordon in Gotham? 2003 Heath Ledger Atletico Madrid 4 Ben McKenzie What is the name of the second book? When did he die? Did they win the Super Cup the previous year? Which was released first: Houses of the Holy or Physical Graffiti? What about Bullock? The War of the Dwarves 22 January 2008 No Houses of the Holy Donal Logue Who is the author? Batman actor? Which club was the winner? Is the rain song and immigrant song there? Creator? Markus Heitz Christian Bale Real Madrid C.F. No Bruno Heller In which city was he born? Director? Which English club did Costa play for before returning to Atletico Madrid? Who wrote those songs? Married to in 2017? Homburg Christopher Nolan Chelsea F.C. Jimmy Page Miranda Cowley When was he born? Sequel name? Which stadium is this club's home ground? Name of his previous band? Wedding date first wife? 10 October 1971 The Dark Knight Rises Stamford Bridge The Yardbirds 19 June 1993 RESULTS ★ Evaluation on our ConvQuestions benchmark ConvQuestions: realistic benchmark on Conversational KG-QA TURN 1 q 1 : And Alan Arkin was behind …? a 1 : Schmendrick TURN 2 q 2 : So who performed the songs? a 2 : America TURN 3 q 3 : Genre of this band’s music? a 3 : Folk Rock TURN 0 q 0 : Which actor voiced the character Unicorn in The Last Unicorn? a 0 : Mia Farrow CONVEX Any KG-QA System + off-the-shelf NERD System TURN 4 q 4 : By the way, who directed the movie? a 4 : Jules Bass ! " # Added at current t Answer at current t Frontiers at current t Predicate node Entity node Initial entity Legend Class node Schmendrick voice actor character role Alan Arkin The Last Unicorn character role voice actor Mia Farrow The Unicorn performer soundtrack album The Last Unicorn Soundtrack America genre Folk Rock band Schmendrick voice actor character role Alan Arkin The Last Unicorn character role voice actor Mia Farrow The Unicorn performer soundtrack album The Last Unicorn Soundtrack America genre Folk Rock director Jules Bass film band The Last Unicorn character role voice actor Mia Farrow The Unicorn Schmendrick voice actor character role Alan Arkin The Last Unicorn character role voice actor Mia Farrow The Unicorn performer soundtrack album The Last Unicorn Soundtrack America Schmendrick voice actor character role Alan Arkin The Last Unicorn character role voice actor Mia Farrow The Unicorn ! " $ ! " % ! " &