update: Makefile
fix
n2pos pos2n
fix: n2pos and pos2n
tried
Merge branch 'master' into develop

Conflicts:
	binsearch.v
	btree.v
delete: isBst
Merge branch 'master' into develop

Conflicts:
	binsearch.v
redefine and proof: isBst
fix
Merge branch 'develop'
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