// Souffle - A Datalog Compiler
// Copyright (c) 2017, The Souffle Developers. All rights reserved
// Licensed under the Universal Permissive License v 1.0 as shown at:
// - https://opensource.org/licenses/UPL
// - <souffle root>/licenses/SOUFFLE-UPL.txt

.type Word <: symbol

.decl words (i:number, w:Word)
.input words

.decl bigram (w:Word, w1:Word)
.output bigram

bigram(w, w1) :- words(i, w), words(i+1, w1).
