blog/assets/js/534d4833.162e2ecd.js

"use strict";(self.webpackChunkfi=self.webpackChunkfi||[]).push([[9771],{93019:(e,t,n)=>{n.r(t),n.d(t,{assets:()=>l,contentTitle:()=>r,default:()=>d,frontMatter:()=>o,metadata:()=>a,toc:()=>c});var s=n(85893),i=n(11151);const o={id:"postcondition-ambiguity",title:"Vague postconditions and proving correctness of algorithms",description:"Debugging and testing with precise postconditions.\n",tags:["python","testing","postconditions","sorting"],last_update:{date:new Date("2021-03-18T00:00:00.000Z")}},r=void 0,a={id:"algorithms-correctness/postcondition-ambiguity",title:"Vague postconditions and proving correctness of algorithms",description:"Debugging and testing with precise postconditions.\n",source:"@site/algorithms/02-algorithms-correctness/2021-03-18-postcondition-ambiguity.md",sourceDirName:"02-algorithms-correctness",slug:"/algorithms-correctness/postcondition-ambiguity",permalink:"/algorithms/algorithms-correctness/postcondition-ambiguity",draft:!1,unlisted:!1,editUrl:"https://github.com/mfocko/blog/tree/main/algorithms/02-algorithms-correctness/2021-03-18-postcondition-ambiguity.md",tags:[{label:"python",permalink:"/algorithms/tags/python"},{label:"testing",permalink:"/algorithms/tags/testing"},{label:"postconditions",permalink:"/algorithms/tags/postconditions"},{label:"sorting",permalink:"/algorithms/tags/sorting"}],version:"current",lastUpdatedAt:1616025600,formattedLastUpdatedAt:"Mar 18, 2021",frontMatter:{id:"postcondition-ambiguity",title:"Vague postconditions and proving correctness of algorithms",description:"Debugging and testing with precise postconditions.\n",tags:["python","testing","postconditions","sorting"],last_update:{date:"2021-03-18T00:00:00.000Z"}},sidebar:"autogeneratedBar",previous:{title:"Algorithms and Correctness",permalink:"/algorithms/category/algorithms-and-correctness"},next:{title:"Asymptotic Notation and Time Complexity",permalink:"/algorithms/category/asymptotic-notation-and-time-complexity"}},l={},c=[{value:"Introduction",id:"introduction",level:2},{value:"Implementation of select sort from the exercises",id:"implementation-of-select-sort-from-the-exercises",level:2},{value:"Discussed preconditions, loop invariants and postconditions",id:"discussed-preconditions-loop-invariants-and-postconditions",level:2},{value:"Precondition",id:"precondition",level:3},{value:"Loop invariant",id:"loop-invariant",level:3},{value:"Postcondition",id:"postcondition",level:3},{value:"So is the permutation really required?",id:"so-is-the-permutation-really-required",level:2},{value:"Implementation of the broken select sort",id:"implementation-of-the-broken-select-sort",level:2},{value:"Property-based tests for our sorts",id:"property-based-tests-for-our-sorts",level:2},{value:"Loop invariant",id:"loop-invariant-1",level:3},{value:"Postcondition(s)",id:"postconditions",level:3},{value:"Putting it together",id:"putting-it-together",level:3},{value:"Let's run the tests!",id:"lets-run-the-tests",level:3},{value:"Summary",id:"summary",level:2}];function h(e){const t={a:"a",admonition:"admonition",annotation:"annotation",blockquote:"blockquote",code:"code",em:"em",h2:"h2",h3:"h3",li:"li",math:"math",mi:"mi",mrow:"mrow",ol:"ol",p:"p",pre:"pre",semantics:"semantics",span:"span",strong:"strong",ul:"ul",...(0,i.a)(),...e.components};return(0,s.jsxs)(s.Fragment,{children:[(0,s.jsx)(t.h2,{id:"introduction",children:"Introduction"}),"\n",(0,s.jsxs)(t.p,{children:[(0,s.jsx)(t.a,{href:"pathname:///files/algorithms/algorithms-correctness/postcondition-ambiguity/test_sort.py",children:"Source code"})," used later on."]}),"\n",(0,s.jsx)(t.h2,{id:"implementation-of-select-sort-from-the-exercises",children:"Implementation of select sort from the exercises"}),"\n",(0,s.jsxs)(t.p,{children:["To implement select sort from the exercises and make it as easy to read as possible, I have implemented maximum function that returns index of the biggest element from the first ",(0,s.jsxs)(t.span,{className:"katex",children:[(0,s.jsx)(t.span,{className:"katex-mathml",children:(0,s.jsx)(t.math,{xmlns:"http://www.w3.org/1998/Math/Math