The Berkeley Crossword Solver – The Berkeley Synthetic Intelligence Analysis Weblog

We not too long ago printed the Berkeley Crossword Solver (BCS), the present cutting-edge for fixing American-style crossword puzzles. The BCS combines neural query answering and probabilistic inference to realize near-perfect efficiency on most American-style crossword puzzles, just like the one proven beneath:

Determine 1: Instance American-style crossword puzzle

An earlier model of the BCS, along side Dr.Fill, was the primary pc program to outscore all human rivals on the planet’s high crossword event. The newest model is the present top-performing system on crossword puzzles from The New York Instances, reaching 99.7% letter accuracy (see the technical paper, net demo, and code launch).

Crosswords are difficult for people and computer systems alike. Many clues are obscure or underspecified and may’t be answered till crossing constraints are taken into consideration. Whereas some clues are just like factoid query answering, others require relational reasoning or understanding troublesome wordplay.

Listed below are a handful of instance clues from our dataset (solutions on the backside of this publish):

  • They’re given out at Berkeley’s HAAS Faculty (4)
  • Winter hrs. in Berkeley (3)
  • Area ender that UC Berkeley was one of many first colleges to undertake (3)
  • Angeleno at Berkeley, say (8)

The BCS makes use of a two-step course of to resolve crossword puzzles. First, it generates a chance distribution over doable solutions to every clue utilizing a query answering (QA) mannequin; second, it makes use of probabilistic inference, mixed with native search and a generative language mannequin, to deal with conflicts between proposed intersecting solutions.

Determine 2: Structure diagram of the Berkeley Crossword Solver

The BCS’s query answering mannequin relies on DPR (Karpukhin et al., 2020), which is a bi-encoder mannequin sometimes used to retrieve passages which are related to a given query. Relatively than passages, nevertheless, our method maps each questions and solutions right into a shared embedding house and finds solutions instantly. In comparison with the earlier state-of-the-art technique for answering crossword clues, this method obtained a 13.4% absolute enchancment in top-1000 QA accuracy. We carried out a handbook error evaluation and located that our QA mannequin sometimes carried out effectively on questions involving data, commonsense reasoning, and definitions, but it surely usually struggled to know wordplay or theme-related clues.

After working the QA mannequin on every clue, the BCS runs crazy perception propagation to iteratively replace the reply possibilities within the grid. This enables data from excessive confidence predictions to propagate to tougher clues. After perception propagation converges, the BCS obtains an preliminary puzzle answer by greedily taking the best chance reply at every place.

The BCS then refines this answer utilizing a neighborhood search that tries to exchange low confidence characters within the grid. Native search works through the use of a guided proposal distribution wherein characters that had decrease marginal possibilities throughout perception propagation are iteratively changed till a regionally optimum answer is discovered. We rating these alternate characters utilizing a character-level language mannequin (ByT5, Xue et al., 2022), that handles novel solutions higher than our closed-book QA mannequin.

Determine 3: Instance adjustments made by our native search process

We evaluated the BCS on puzzles from 5 main crossword publishers, together with The New York Instances. Our system obtains 99.7% letter accuracy on common, which jumps to 99.9% in the event you ignore puzzles that contain uncommon themes. It solves 81.7% of puzzles with out a single mistake, which is a 24.8% enchancment over the earlier state-of-the-art system.

Determine 4: Outcomes in comparison with earlier state-of-the-art Dr.Fill

The American Crossword Puzzle Match (ACPT) is the most important and longest-running crossword event and is organized by Will Shortz, the New York Instances crossword editor. Two prior approaches to pc crossword fixing gained mainstream consideration and competed within the ACPT: Proverb and Dr.Fill. Proverb is a 1998 system that ranked 213th out of 252 rivals within the event. Dr.Fill’s first competitors was in ACPT 2012, and it ranked 141st out of 650 rivals. We teamed up with Dr.Fill’s creator Matt Ginsberg and mixed an early model of our QA system with Dr.Fill’s search process to outscore all 1033 human rivals within the 2021 ACPT. Our joint submission solved all seven puzzles in beneath a minute, lacking simply three letters throughout two puzzles.

Determine 5: Outcomes from the 2021 American Crossword Puzzle Match (ACPT)

We’re actually excited in regards to the challenges that stay in crosswords, together with dealing with troublesome themes and extra complicated wordplay. To encourage future work, we’re releasing a dataset of 6.4M query reply clues, a demo of the Berkeley Crossword Solver, and our code at

Solutions to clues: MBAS, PST, EDU, INSTATER

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