I am trying to prove a theorem but got stuck at a subgoal (that I prefer to skip and prove later). How can I skip this and prove the others ? First, I tried oops and sorry but they both abort the entire proof (instead of the only subgoal). I...

I would like to create a quotient type with quotient_type in Isabelle/HOL in which I would left "non-constructed" the non-empty set S and the equivalence relation ≡. The goal is for me to derive generic properties w.r.t. S and ≡ over the quotient-lifted set S/≡. In this way, it would...

Perhaps this is a stupid question. Here's a quote from the Hasochism paper: One approach to resolving this issue is to encode lemmas, given by parameterised equations, as Haskell functions. In general, such lemmas may be encoded as functions of type: ∀ x1 ... xn. Natty x1 → ... →...

How to prove forall n m : nat, (n <? m) = false -> m <= n in Coq? I got as far as turning the conclusion into ~ n < m using by apply Nat.nlt_ge. Doing SearchAbout ltb yields ltb_lt: forall n m : nat, (n <? m) =...

I am trying to install the paradox theorem prover sourced from here. When I run the makefile this is the command that runs: ghc -optl -static -lstdc++ -I../instantiate -I../minisat/current-base ../minisat/current-base/Solver.or ../minisat/current-base/Prop.or ../instantiate/MiniSatWrapper.or ../instantiate/MiniSatInstantiateClause.or -fglasgow-exts -O2 -static -threaded -main-is Paradox.Main.main --make Paradox.Main -o paradox And it results in several errors like...

I'm trying to do a modified proof of compile_correct from the first chapter of Certified Programming with Dependent Types. In my version, I try to make use of the fact that progDenote is a fold, and use a weaker inductive hypothesis in the proof of the main lemma in priving...

In Isabelle, I often find that I can prove a goal successfully using different solvers. Generally I would prefer to use the weakest solver that can just about prove the goal. Based on my experience with Isabelle so far, my current understanding is that in order of increasing strength and...

I need one more lemma showing that inj₁ x ≡ inj₂ y is absurd as part of a larger theorem about disjoint union types (⊎) in Agda. This result would follow directly from the two constructors for ⊎, namely inj₁ and inj₂, being disjoint. Is that the case in Agda?...

The problem I am wondering if is there a natural way of encoding in Isabelle a grammar like this: type_synonym Var = string datatype Value = VInt int | ... datatype Cmd = Skip | NonDeterministicChoice "Cmd set" | ... The motivation would be to give definition a few specification...

Every goal that I have encountered in Isabelle so far that could be solved using arith could also be solved by presburger and vice versa, for example lemma "odd (n::nat) ⟹ Suc (2 * (n div 2)) = n" by presburger (* or arith *) What's the difference between the...