From 178fa393176e633dd06c818e644f0388dccf6c67 Mon Sep 17 00:00:00 2001
From: Robbert Krebbers
Date: Mon, 8 Jan 2018 11:26:23 0800
Subject: [PATCH] Remove duplicate README.

exercises/ProofMode.md => ProofMode.md  0
exercises/README.md => README.md  0
solutions/ProofMode.md  322 
solutions/README.md  51 
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Tactic overview
===============

Many of the tactics below apply to more goals than described in this document
since the behavior of these tactics can be tuned via instances of the type
classes in the file [proofmode/classes](proofmode/classes.v). Most notable, many
of the tactics can be applied when the to be introduced or to be eliminated
connective appears under a later, an update modality, or in the conclusion of a
weakest precondition.

Applying hypotheses and lemmas


 `iExact "H"` : finish the goal if the conclusion matches the hypothesis `H`
 `iAssumption` : finish the goal if the conclusion matches any hypothesis
 `iApply pm_trm` : match the conclusion of the current goal against the
 conclusion of `pm_trm` and generates goals for the premises of `pm_trm`. See
 proof mode terms below.
 If the applied term has more premises than given specialization patterns, the
 pattern is extended with `[] ... []`. As a consequence, all unused spatial
 hypotheses move to the last premise.

Context management


 `iIntros (x1 ... xn) "ipat1 ... ipatn"` : introduce universal quantifiers
 using Coq introduction patterns `x1 ... xn` and implications/wands using proof
 mode introduction patterns `ipat1 ... ipatn`.
 `iClear (x1 ... xn) "selpat"` : clear the hypotheses given by the selection
 pattern `selpat` and the Coq level hypotheses/variables `x1 ... xn`.
 `iRevert (x1 ... xn) "selpat"` : revert the hypotheses given by the selection
 pattern `selpat` into wands, and the Coq level hypotheses/variables
 `x1 ... xn` into universal quantifiers. Persistent hypotheses are wrapped into
 the persistence modality.
 `iRename "H1" into "H2"` : rename the hypothesis `H1` into `H2`.
 `iSpecialize pm_trm` : instantiate universal quantifiers and eliminate
 implications/wands of a hypothesis `pm_trm`. See proof mode terms below.
 `iSpecialize pm_trm as #` : instantiate universal quantifiers and eliminate
 implications/wands of a hypothesis whose conclusion is persistent. In this
 case, all hypotheses can be used for proving the premises, as well as for
 the resulting goal.
 `iPoseProof pm_trm as (x1 ... xn) "ipat"` : put `pm_trm` into the context and
 eliminates it. This tactic is essentially the same as `iDestruct` with the
 difference that when `pm_trm` is a nonuniverisally quantified spatial
 hypothesis, it will not throw the hypothesis away.
 `iAssert P with "spat" as "ipat"` : generates a new subgoal `P` and adds the
 hypothesis `P` to the current goal. The specialization pattern `spat`
 specifies which hypotheses will be consumed by proving `P`. The introduction
 pattern `ipat` specifies how to eliminate `P`.
 In case all branches of `ipat` start with a `#` (which causes `P` to be moved
 to the persistent context) or with an `%` (which causes `P` to be moved to the
 pure Coq context), then one can use all hypotheses for proving `P` as well as
 for proving the current goal.
 `iAssert P as %cpat` : assert `P` and eliminate it using the Coq introduction
 pattern `cpat`. All hypotheses can be used for proving `P` as well as for
 proving the current goal.

Introduction of logical connectives


 `iPureIntro` : turn a pure goal into a Coq goal. This tactic works for goals
 of the shape `⌜φ⌝`, `a ≡ b` on discrete COFEs, and `✓ a` on discrete CMRAs.

 `iLeft` : left introduction of disjunction.
 `iRight` : right introduction of disjunction.

 `iSplit` : introduction of a conjunction, or separating conjunction provided
 one of the operands is persistent.
 `iSplitL "H1 ... Hn"` : introduction of a separating conjunction. The
 hypotheses `H1 ... Hn` are used for the left conjunct, and the remaining ones
 for the right conjunct. Persistent hypotheses are ignored, since these do not
 need to be split.
 `iSplitR "H0 ... Hn"` : symmetric version of the above.
 `iExist t1, .., tn` : introduction of an existential quantifier.

Elimination of logical connectives


 `iExFalso` : Ex falso sequitur quod libet.
 `iDestruct pm_trm as (x1 ... xn) "ipat"` : elimination of a series of
 existential quantifiers using Coq introduction patterns `x1 ... xn`, and
 elimination of an object level connective using the proof mode introduction
 pattern `ipat`.
 In case all branches of `ipat` start with a `#` (which causes the hypothesis
 to be moved to the persistent context) or with an `%` (which causes the
 hypothesis to be moved to the pure Coq context), then one can use all
 hypotheses for proving the premises of `pm_trm`, as well as for proving the
 resulting goal. Note that in this case the hypotheses still need to be
 subdivided among the spatial premises.
 `iDestruct pm_trm as %cpat` : elimination of a pure hypothesis using the Coq
 introduction pattern `cpat`. When using this tactic, all hypotheses can be
 used for proving the premises of `pm_trm`, as well as for proving the
 resulting goal.

Separating logic specific tactics


 `iFrame (t1 .. tn) "selpat"` : cancel the Coq terms (or Coq hypotheses)
 `t1 ... tn` and Iris hypotheses given by `selpat` in the goal. The constructs
 of the selection pattern have the following meaning:

 + `%` : repeatedly frame hypotheses from the Coq context.
 + `#` : repeatedly frame hypotheses from the persistent context.
 + `∗` : frame as much of the spatial context as possible.

 Notice that framing spatial hypotheses makes them disappear, but framing Coq
 or persistent hypotheses does not make them disappear.

 This tactic finishes the goal in case everything in the conclusion has been
 framed.
 `iCombine "H1" "H2" as "H"` : turns `H1 : P1` and `H2 : P2` into
 `H : P1 ∗ P2`.

Modalities


 `iModIntro` : introduction of a modality that is an instance of the
 `FromModal` type class. Instances include: later, except 0, basic update and
 fancy update.
 `iMod pm_trm as (x1 ... xn) "ipat"` : eliminate a modality `pm_trm` that is
 an instance of the `ElimModal` type class. Instances include: later, except 0,
 basic update and fancy update.

The persistence and plainness modalities


 `iAlways` : introduce a persistence or plainness modality and the spatial
 context. In case of a plainness modality, the tactic will prune all persistent
 hypotheses that are not plain.

The later modality


 `iNext n` : introduce `n` laters by stripping that number of laters from all
 hypotheses. If the argument `n` is not given, it strips one later if the
 leftmost conjunct is of the shape `▷ P`, or `n` laters if the leftmost
 conjunct is of the shape `▷^n P`.
 `iLöb as "IH" forall (x1 ... xn) "selpat"` : perform Löb induction by
 generating a hypothesis `IH : ▷ goal`. The tactic generalizes over the Coq
 level variables `x1 ... xn`, the hypotheses given by the selection pattern
 `selpat`, and the spatial context.

Induction


 `iInduction x as cpat "IH" forall (x1 ... xn) "selpat"` : perform induction on
 the Coq term `x`. The Coq introduction pattern is used to name the introduced
 variables. The induction hypotheses are inserted into the persistent context
 and given fresh names prefixed `IH`. The tactic generalizes over the Coq level
 variables `x1 ... xn`, the hypotheses given by the selection pattern `selpat`,
 and the spatial context.

Rewriting


 `iRewrite pm_trm` : rewrite an equality in the conclusion.
 `iRewrite pm_trm in "H"` : rewrite an equality in the hypothesis `H`.

Iris


 `iInv N as (x1 ... xn) "ipat" "Hclose"` : open the invariant `N`, the update
 for closing the invariant is put in a hypothesis named `Hclose`.

Miscellaneous


 The tactic `done` is extended so that it also performs `iAssumption` and
 introduces pure connectives.
 The proof mode adds hints to the core `eauto` database so that `eauto`
 automatically introduces: conjunctions and disjunctions, universal and
 existential quantifiers, implications and wand, plainness, persistence, later
 and update modalities, and pure connectives.

Selection patterns
==================

Selection patterns are used to select hypotheses in the tactics `iRevert`,
`iClear`, `iFrame`, `iLöb` and `iInduction`. The proof mode supports the
following _selection patterns_:

 `H` : select the hypothesis named `H`.
 `%` : select the entire pure/Coq context.
 `#` : select the entire persistent context.
 `∗` : select the entire spatial context.

Introduction patterns
=====================

Introduction patterns are used to perform introductions and eliminations of
multiple connectives on the fly. The proof mode supports the following
_introduction patterns_:

 `H` : create a hypothesis named `H`.
 `?` : create an anonymous hypothesis.
 `_` : remove the hypothesis.
 `$` : frame the hypothesis in the goal.
 `[ipat1 ipat2]` : (separating) conjunction elimination. In order to eliminate
 conjunctions `P ∧ Q` in the spatial context, one of the following conditions
 should hold:
 + Either the proposition `P` or `Q` should be persistent.
 + Either `ipat1` or `ipat2` should be `_`, which results in one of the
 conjuncts to be thrown away.
 `[ipat1ipat2]` : disjunction elimination.
 `[]` : false elimination.
 `%` : move the hypothesis to the pure Coq context (anonymously).
 `>` and `<` : rewrite using a pure Coq equality
 `# ipat` : move the hypothesis to the persistent context.
 `> ipat` : eliminate a modality (if the goal permits).

Apart from this, there are the following introduction patterns that can only
appear at the top level:

 `{selpat}` : clear the hypotheses given by the selection pattern `selpat`.
 Items of the selection pattern can be prefixed with `$`, which cause them to
 be framed instead of cleared.
 `!%` : introduce a pure goal (and leave the proof mode).
 `!#` : introduce an persistence or plainness modality (by calling `iAlways`).
 `!>` : introduce a modality (by calling `iModIntro`).
 `/=` : perform `simpl`.
 `//` : perform `try done` on all goals.
 `//=` : syntactic sugar for `/= //`
 `*` : introduce all universal quantifiers.
 `**` : introduce all universal quantifiers, as well as all arrows and wands.

For example, given:

 ∀ x, x = 0 ⊢ □ (P → False ∨ □ (Q ∧ ▷ R) ∗ P ∗ ▷ (R ∗ Q ∧ x = pred 2)).

You can write

 iIntros (x) "% !# $ [[]  #[HQ HR]] /= !>".

which results in:

 x : nat
 H : x = 0
 ______________________________________(1/1)
 "HQ" : Q
 "HR" : R
 □
 R ∗ Q ∧ x = 1


Specialization patterns
=======================

Since we are reasoning in a spatial logic, when eliminating a lemma or
hypothesis of type ``P_0 ∗ ... ∗ P_n ∗ R``, one has to specify how the
hypotheses are split between the premises. The proof mode supports the following
_specification patterns_ to express splitting of hypotheses:

 `H` : use the hypothesis `H` (it should match the premise exactly). If `H` is
 spatial, it will be consumed.

 `[H1 .. Hn]` and `[H1 .. Hn //]` : generate a goal for the premise with the
 (spatial) hypotheses `H1 ... Hn` and all persistent hypotheses. The spatial
 hypotheses among `H1 ... Hn` will be consumed, and will not be available for
 subsequent goals. Hypotheses prefixed with a `$` will be framed in the
 goal for the premise. The pattern can be terminated with a `//`, which causes
 `done` to be called to close the goal (after framing).
 `[H1 ... Hn]` and `[H1 ... Hn //]` : the negated forms of the above
 patterns, where the goal for the premise will have all spatial premises except
 `H1 .. Hn`.

 `[> H1 ... Hn]` and `[> H1 ... Hn //]` : like the above patterns, but these
 patterns can only be used if the goal is a modality `M`, in which case
 the goal for the premise will be wrapped in the modality `M`.
 `[> H1 ... Hn]` and `[> H1 ... Hn //]` : the negated forms of the above
 patterns.

 `[# $H1 .. $Hn]` and `[# $H1 .. $Hn //]` : generate a goal for a persistent
 premise in which all hypotheses are available. This pattern does not consume
 any hypotheses; all hypotheses are available in the goal for the premise, as
 well in the subsequent goal. The hypotheses `$H1 ... $Hn` will be framed in
 the goal for the premise. These patterns can be terminated with a `//`, which
 causes `done` to be called to close the goal (after framing).
 `[%]` and `[% //]` : generate a Coq goal for a pure premise. This pattern
 does not consume any hypotheses. The pattern can be terminated with a `//`,
 which causes `done` to be called to close the goal.

 `[$]` : solve the premise by framing. It will first repeatedly frame the
 spatial hypotheses, and then repeatedly frame the persistent hypotheses.
 Spatial hypothesis that are not framed are carried over to the subsequent
 goal.
 `[> $]` : like the above pattern, but this pattern can only be used if the
 goal is a modality `M`, in which case the goal for the premise will be wrapped
 in the modality `M` before framing.
 `[# $]` : solve the persistent premise by framing. It will first repeatedly
 frame the spatial hypotheses, and then repeatedly frame the persistent
 hypotheses. This pattern does not consume any hypotheses.

For example, given:

 H : □ P ∗ P 2 ∗ R ∗ x = 0 ∗ Q1 ∗ Q2

One can write:

 iDestruct ("H" with "[#] [H1 $H2] [$] [% //]") as "[H4 H5]".


Proof mode terms
================

Many of the proof mode tactics (such as `iDestruct`, `iApply`, `iRewrite`) can
take both hypotheses and lemmas, and allow one to instantiate universal
quantifiers and implications/wands of these hypotheses/lemmas on the fly.

The syntax for the arguments of these tactics, called _proof mode terms_, is:

 (H $! t1 ... tn with "spat1 .. spatn")

Here, `H` can be both a hypothesis, as well as a Coq lemma whose conclusion is
of the shape `P ⊢ Q`. In the above, `t1 ... tn` are arbitrary Coq terms used
for instantiation of universal quantifiers, and `spat1 .. spatn` are
specialization patterns to eliminate implications and wands.

Proof mode terms can be written down using the following short hands too:

 (H with "spat1 .. spatn")
 (H $! t1 ... tn)
 H
diff git a/solutions/README.md b/solutions/README.md
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# The Iris tutorial @ POPL'18

For the tutorial material you need to have the following dependencies installed:

 Coq 8.6.1 / 8.7.0 / 8.7.1
 Ssreflect 1.6.4
 Coqstd++ 1.1
 Iris 3.1

*Note:* the tutorial material will not work with earlier versions of Iris, it
is important to install the exact versions as given above.

## Installing Iris via opam

The easiest, and recommend, way of installing Iris and its dependencies is via
the OCaml package manager opam (1.2.2 or newer). You first have to add the Coq
opam repository:

 opam repo add coqreleased https://coq.inria.fr/opam/released

Then you can do `opam install coqiris`.

## Installing Iris from source

If you are unable to use opam, you can also build Iris from source. For this,
make sure to `git checkout` the correct versions, and run `make; make install`
for Ssreflect, Coqstd++ and Iris.

## Compiling the exercises

Run `make` to compile the exercises. You need to have exercise 3 compiled to
work on exercise 4 and 5.

## Documentation

The file `ProofMode.md` in the tutorial material (which can also be found in the
root of the Iris repository) contains a list of the Iris Proof Mode tactics.

If you would like to know more about Iris, we recommend to take a look at:

 http://irisproject.org/tutorialmaterial.html
 Lecture Notes on Iris: HigherOrder Concurrent Separation Logic
 Lars Birkedal and Aleš Bizjak
 Used for an MSc course on concurrent separation logic at Aarhus University

 https://www.mpisws.org/~dreyer/papers/irisgroundup/paper.pdf
 Iris from the Ground Up: A Modular Foundation for HigherOrder Concurrent
 Separation Logic
 Ralf Jung, Robbert Krebbers, JacquesHenri Jourdan, Aleš Bizjak, Lars
 Birkedal, Derek Dreyer.
 A detailed description of the Iris logic and its model

2.26.2