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-Table of Contents
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- Planning The HoTT Game - - -
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-Planning The HoTT Game
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-Aims of the HoTT Game
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- To get mathematicians with no experience in proof verification interested in HoTT and able to use Agda for HoTT -
- [?] Work towards showing an interesting result in HoTT -
- Try to balance hiding cubical implementations whilst exploiting their advantages -
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-Barriers
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- HOLD Installation of emacs -
- TODO Usage of emacs -
- TODO General type theoretic foundations -
- TODO Cubical type theory -
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-Format
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- [?] Everything done in .agda files -
- Partially written code with spaces for participants to fill in + answer files -
- Levels set out with mini-bosses like in Nat Num Game, but with an overall boss -
- [?] Side quests -
- References to Harper lectures and HoTT book -
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-Content
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- emacs usage -
- agda usage
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- basic commands (all covered in https://agda.readthedocs.io/en/v2.6.0.1/getting-started/quick-guide.html) -
- recommend doom emacs -
- implicit/explicit arguments -
- holes and inferred types -
_+_
vsplus__
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- - type theory basics
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- meta (judgemental/definitional) equality vs internal (propositional) equality
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- function extensionality -
- - type formation
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- inductive types
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- (side Q) positive and negative constructions of Pi/Sigma types -
data
andrecord
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- - inductive types
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- universes -
- recursors / pattern matching -
- (side Q) some natural number exercises as early evidence of being able to ’do maths’? -
- different notions of equivalence
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- fibers contractable -
- quasi-inverse -
- zig-zag -
- - (side Q) types are infinity groupoids -
- extra paths (univalence, fun ext, HITs) -
- - meta (judgemental/definitional) equality vs internal (propositional) equality
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- HoTT
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- basics
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- meta interval, identity type vs path type
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- mention identity type for compatability with other sources, but just use path type -
- - path type on other types -
- dependent path type PathP vs path over -
- univalence -
- the (non)-issue of J in (Cu)TT -
- isContr, isProp, isSet -
- drawing pictures -
- - meta interval, identity type vs path type
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- Structures, using univalence to transport
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- transporting results between isomorphic structures -
- - HITs, examples
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- the constructed interval -
- booleans and covers -
- Sn -
- S1 with 2 cw structures equiv -
- - Homotopy n-types
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- homotopy levels being closed under type constructions, in particular Set and ETT inside HoTT
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- in particular sigma types -
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- - homotopy levels being closed under type constructions, in particular Set and ETT inside HoTT
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- - basics
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-Debriefs
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- 2021 July 15; Homotopy n-types
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- watched (Harper) lecture 15 on Sets being closed under type formations ->- motivates showing in Agda Sets closed under Sigma. -
- Harper does product case, claiming sigma case follows analogously, -
- attempt proof in Cubical Agda but highly non-obvious how to use that fibers are Sets. -
- difficulty is that PathP not in one fiber, but PathOver is, AND PathOver <-> PathP NON-obvious -
- Easy to generalize situation to n-types being closed under Sigma (7.1.8 in HoTT book), we showed this assuming PathPIsoPath -
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