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Try doing some basic maths questions in the Lean Theorem Prover. Functions, real numbers, equivalence relations and groups. Click on README.md and then on "Open in CoCalc with one click".

Project: Xena
Views: 18536
License: APACHE
/-
Copyright (c) 2019 Keeley Hoek. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Keeley Hoek, Floris van Doorn
-/

import logic.basic
meta def error_msg (s : string) : bool := @undefined_core bool $ s ++ ".decidable not inlined"

meta def examine (b : Prop) [decidable b] : bool := b

#eval examine $ ff ∧ (error_msg "and")
#eval examine $ tt ∨ (error_msg "or")