Markdown preview
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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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