1. 24 Jan, 2018 1 commit
  2. 13 Nov, 2017 1 commit
    • Robbert Krebbers's avatar
      Improved treatment of anonymous hypotheses in the proof mode. · bb3584e7
      Robbert Krebbers authored
      The proof mode now explicitly keeps track of anonymous hypotheses (i.e.
      hypotheses that are introduced by the introduction pattern `?`). Consider:
      
        Lemma foo {M} (P Q R : uPred M) : P -∗ (Q ∗ R) -∗ Q ∗ P.
        Proof. iIntros "? [H ?]". iFrame "H". iFrame. Qed.
      
      After the `iIntros`, the goal will be:
      
        _ : P
        "H" : Q
        _ : R
        --------------------------------------∗
        Q ∗ P
      
      Anonymous hypotheses are displayed in a special way (`_ : P`). An important
      property of the new anonymous hypotheses is that it is no longer possible to
      refer to them by name, whereas before, anonymous hypotheses were given some
      arbitrary fresh name (typically prefixed by `~`).
      
      Note tactics can still operate on these anonymous hypotheses. For example, both
      `iFrame` and `iAssumption`, as well as the symbolic execution tactics, will
      use them. The only thing that is not possible is to refer to them yourself,
      for example, in an introduction, specialization or selection pattern.
      
      Advantages of the new approach:
      
      - Proofs become more robust as one cannot accidentally refer to anonymous
        hypotheses by their fresh name.
      - Fresh name generation becomes considerably easier. Since anonymous hypotheses
        are internally represented by natural numbers (of type `N`), we can just fold
        over the hypotheses and take the max plus one. This thus solve issue #101.
      bb3584e7
  3. 25 Oct, 2017 2 commits
  4. 26 Sep, 2017 1 commit
    • Robbert Krebbers's avatar
      Fix issue #98. · e17ac4ad
      Robbert Krebbers authored
      We used to normalize the goal, and then checked whether it was of
      a certain shape. Since `uPred_valid P` normalized to `True ⊢ P`,
      there was no way of making a distinction between the two, hence
      `True ⊢ P` was treated as `uPred_valid P`.
      
      In this commit, I use type classes to check whether the goal is of
      a certain shape. Since we declared `uPred_valid` as `Typeclasses
      Opaque`, we can now make a distinction between `True ⊢ P` and
      `uPred_valid P`.
      e17ac4ad
  5. 17 Sep, 2017 1 commit
  6. 22 Mar, 2017 1 commit
  7. 11 Jan, 2017 1 commit
  8. 05 Jan, 2017 2 commits
  9. 04 Jan, 2017 1 commit
  10. 03 Jan, 2017 1 commit
  11. 09 Dec, 2016 1 commit
  12. 22 Nov, 2016 2 commits
    • Robbert Krebbers's avatar
      Make nclose an explicit coercion. · 274209c2
      Robbert Krebbers authored
      We do this by introducing a type class UpClose with notation ↑.
      
      The reason for this change is as follows: since `nclose : namespace
      → coPset` is declared as a coercion, the notation `nclose N ⊆ E` was
      pretty printed as `N ⊆ E`. However, `N ⊆ E` could not be typechecked
      because type checking goes from left to right, and as such would look
      for an instance `SubsetEq namespace`, which causes the right hand side
      to be ill-typed.
      274209c2
    • Ralf Jung's avatar
      new notation for pure assertions · 99cbb525
      Ralf Jung authored
      99cbb525
  13. 03 Nov, 2016 1 commit
    • Robbert Krebbers's avatar
      Use symbol ∗ for separating conjunction. · cc31476d
      Robbert Krebbers authored
      The old choice for ★ was a arbitrary: the precedence of the ASCII asterisk *
      was fixed at a wrong level in Coq, so we had to pick another symbol. The ★ was
      a random choice from a unicode chart.
      
      The new symbol ∗ (as proposed by David Swasey) corresponds better to
      conventional practise and matches the symbol we use on paper.
      cc31476d
  14. 28 Oct, 2016 2 commits
  15. 25 Oct, 2016 5 commits
  16. 12 Oct, 2016 1 commit
  17. 05 Oct, 2016 1 commit
  18. 25 Aug, 2016 1 commit
  19. 05 Aug, 2016 3 commits
    • Robbert Krebbers's avatar
      No longer break now_True abstraction. · 51b15fdc
      Robbert Krebbers authored
      And make it Typeclasses Opaque to ensure that we indeed do not do
      so using the proof mode.
      51b15fdc
    • Robbert Krebbers's avatar
      More introduction patterns. · 4d8c4ac8
      Robbert Krebbers authored
      Also make those for introduction and elimination more symmetric:
      
        !%   pure introduction         %        pure elimination
        !#   always introduction       #        always elimination
        !>   later introduction        > pat    timeless later elimination
        !==> view shift introduction   ==> pat  view shift elimination
      4d8c4ac8
    • Robbert Krebbers's avatar
      Iris 3.0: invariants and weakest preconditions encoded in the logic. · 1f589858
      Robbert Krebbers authored
      This commit features:
      
      - A simpler model. The recursive domain equation no longer involves a triple
        containing invariants, physical state and ghost state, but just ghost state.
        Invariants and physical state are encoded using (higher-order) ghost state.
      
      - (Primitive) view shifts are formalized in the logic and all properties about
        it are proven in the logic instead of the model. Instead, the core logic
        features only a notion of raw view shifts which internalizing performing frame
        preserving updates.
      
      - A better behaved notion of mask changing view shifts. In particular, we no
        longer have side-conditions on transitivity of view shifts, and we have a
        rule for introduction of mask changing view shifts |={E1,E2}=> P with
        E2 ⊆ E1 which allows to postpone performing a view shift.
      
      - The weakest precondition connective is formalized in the logic using Banach's
        fixpoint. All properties about the connective are proven in the logic instead
        of directly in the model.
      
      - Adequacy is proven in the logic and uses a primitive form of adequacy for
        uPred that only involves raw views shifts and laters.
      
      Some remarks:
      
      - I have removed binary view shifts. I did not see a way to describe all rules
        of the new mask changing view shifts using those.
      - There is no longer the need for the notion of "frame shifting assertions" and
        these are thus removed. The rules for Hoare triples are thus also stated in
        terms of primitive view shifts.
      
      TODO:
      
      - Maybe rename primitive view shift into something more sensible
      - Figure out a way to deal with closed proofs (see the commented out stuff in
        tests/heap_lang and tests/barrier_client).
      1f589858
  20. 28 Jul, 2016 1 commit
  21. 20 Jul, 2016 1 commit
  22. 13 Jul, 2016 1 commit
  23. 17 Jun, 2016 2 commits
  24. 16 Jun, 2016 1 commit
  25. 01 Jun, 2016 2 commits
  26. 31 May, 2016 2 commits
  27. 25 May, 2016 1 commit