Hackers' Pub

Syntax	Description	Examples
`"` keyword `"`	Finds the string within quotes, including spaces. Case-insensitive. (Escape quotes inside with `\"`)	`"Hackers' Pub"`
`from:` handle	Finds content written by the specified user.	`from:hongminhee` `from:hongminhee@hollo.social`
`lang:` ISO 639-1	Finds content written in the specified language.	`lang:en`
`#` tag	Finds content with the specified tag. Case-insensitive.	`#HackersPub`
condition condition	Finds content that satisfies both conditions on either side of the space (logical AND).	`"Hackers' Pub" lang:en`
condition `OR` condition	Finds content that satisfies at least one of the conditions on either side of the OR operator (logical OR).	`#HackersPub OR "Hackers' Pub" lang:en`
`(` condition `)`	Combines the operators within the parentheses first.	`(#HackersPub OR "Hackers' Pub" OR "Hackers Pub") lang:en`

José A. Alonso @Jose_A_Alonso@mathstodon.xyz

4/13/2025, 3:06:13 PM

Public

#Calculemus: Demostraciones con Lean4 y con Isabelle/HOL de "Si f es suprayectiva, entonces u ⊆ f[f⁻¹[u]]". https://jaalonso.github.io/calculemus/posts/2021/06/11-imagen_de_imagen_inversa_de_aplicaciones_suprayectivas/ #LeanProver #IsabelleHOL #Math

Si f es suprayectiva, entonces u ⊆ f[f⁻¹[u]]

Demostrar con Lean4 y con Isabelle/HOL que si \(f\) es suprayectiva, entonces \[ u ⊆ f[f⁻¹[u]] \] Para ello, completar la siguiente teoría de Lean4: import Mathlib.Data.Set.Function open Set Function

jaalonso.github.io · Calculemus

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