Add alternative proof for 1964_p1b #101

	name: pull request

	on:
	pull_request:
	branches: [ main ]

	jobs:
	build:
	name: Build
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4

	- name: install elan
	run: \|
	set -o pipefail
	curl https://raw.githubusercontent.com/leanprover/elan/master/elan-init.sh -sSf \| sh -s -- --default-toolchain none -y
	~/.elan/bin/lean --version
	echo "$HOME/.elan/bin" >> $GITHUB_PATH
	echo "short_lean_version=$(~/.elan/bin/lean --run scripts/lean_version.lean)" >> $GITHUB_ENV

	- name: get mathlib cache
	run: lake exe cache get

	- name: lake build
	id: build
	run: \|
	set -o pipefail
	echo "Starting build at $(date +'%T')"
	lake build
	result_run1=$?
	echo "Complete at $(date +'%T'); return value $result_run1"

	- name: check that Compfiles.lean is up to date
	id: check-Compfiles-lean
	run: \|
	echo "Running mk_toplevel_file.bash..."
	bash ./scripts/mk_toplevel_file.bash
	echo "Checking that Compfiles.lean is unchanged..."
	echo "(If this fails, you should run ./scripts/mk_toplevel_file.bash locally.)"
	bash ./scripts/assert_working_directory_clean.bash

	- name: run extractProblems
	id: run-extractProblems
	run: \|
	set -o pipefail
	echo "Starting build at $(date +'%T')"
	lake exe extractProblems
	result_run1=$?
	echo "Complete at $(date +'%T'); return value $result_run1"

	- name: run buildWebpage
	id: run-buildWebpage
	env:
	GITHUB_PAGES_BASEURL: https://dwrensha.github.io/compfiles/
	run: \|
	set -o pipefail
	echo "Starting build at $(date +'%T')"
	lake exe buildWebpage
	result_run1=$?
	echo "Complete at $(date +'%T'); return value $result_run1"

Provide feedback