A* Search

[@NikosXouselas10]

Absolute legend. This dude has literally been more helpfull than I could ever imagine! Insane work!

[@mostafakarimi1733]

One of the best explanation of A* algorithm I've ever seen, Thank you Sir and I hope you create more videos about AI

[@terrycamerlengo5492]

This channel with John Levine is awesome. What a great lecturer! Great channel! Thank you!

[@mishalubich7141]

Best A* tutorial for run-through! Others jump around (computerphile) too much, and its not easy to get a grasp of how we can run this algorithm by hand and how it actually works (abstracting away all the data structures). Thank you so much!

[@nitinneo7]

The most coherent explanation of A* algorithm with an example. Thank you for saving our time and energy.

[@whiningmachine]

Thank you for this explanation. You have no idea how many pages and videos I had to go through before somebody explained that the heuristic indicates the estimated cost to a goal node. I had no idea why we only added the destination node's heuristic to the total (and not the other nodes' heuristics along the path), and now I know. Thanks!

[@dennissaluaar9103]

I am studying an introductory course in Artificial Intelligence here in Gothenburg, this short lecture made the A* very clear to me. Thank you!

[@tollwutpinguin]

Thank you for providing free educational content of such high quality! The world needs more lecturers like yourself

[@zaid_marridi]

Thank you for this simple and great explanation... You're simply the best at this. Clean, clear, easy and very informative What else could someone ask for?!!!

[@iampujan]

Loved the video. Clear and Understandable. Thanks Professor John. Looking forward for more videos.

[@simongrome9073]

These videos are super helpful in explaining stuff I didn't get from my textbook! Thank you!

[@555to_infinity]

Wow. Perfect lecture on A* search. Highly recommended!

[@lianghaoquan]

Thank you for this great video! Love your clear explanation and your voice!

[@husseinsylla4850]

Hello Sir, Best tutorial I have covered on A* algorithms. Clear and complete, include all explanations for f(n)=g(n)+h(n) and over-estimations of theoritical heuristics. Brilliant. Thank you so much.

[@cuchuoisalay9263]

I would like to say thanks to you. Your tutorial about A* is very exciting!

[@LucasofAppalachia]

Absolutely phenomenal explanation. Thank you for this.

[@KuliahInformatika]

I love the way you explain the algorithm... easy to understand...

[@nihilrocks]

Truly a godsend! Saved me 5 marks on my A levels 15mins before the exam. Couldn't have explained it better!

[@OsamaAlmas]

This is amazing, You deserve more subscribers!!!

[@HafizAsimNawaz]

I love this man...... you rocked sir... hats off

[@johnlevine2909]

Thank you! Glad you found it useful.

[@tashijawed5472]

Great Explanation, as always. Just want to add one thing. at 9:43 When we reached node G2 with a cost of 13, we will stop the algorithm and won't go further with "E" node. Why? because it uses Priority Queue, the algorithm will stop once it finds a Goal node with a cost "less than or equal" to costs of other nodes. And it makes sense!! because once you reached G2 with a cost of 13, even if you have another node with the same cost, there's no point in checking it because it will only add to the cost.

[@peterlawrence3505]

But if the heuristic was not admissible this would not be the case right?

[@NinaHProductions1]

You are the best teacher and provide the cleanest of explanations - at 5:53 the A* score for A is 17 (5 + 3 +2 + 7) instead of 20 I think?

[@que_93]

It should be 17, not 20.

[@ngusumakofu1]

Indeed it should be 17

[@JackyShaw]

I agree too.

[@know_how5661]

yup... its 17

[@sussananukem7101]

Nope... He's correct. He readded the path cost from A to B since we are revisiting A. That is: 5+3+(3)+2+7 =20

[@Peter-bg1ku]

Your explanation is amazing. Thank you!

[@nilsmartel2295]

you're a most talented teacher. Thank you

[@nethmagunathilaka41]

Best place to learn A*. U save my day!

[@TheSophiaLight]

Clear, patient, simple. Thank you.

[@breadsteeth2562]

Love from China. Clear explanation and it helps me a lot. Thank you!

[@abdolvakilfazli2488]

Insanely clear explanation. Hope you add more details about completeness, optimality and complexity

[@saiprasad8311]

Good example. Makes it so easy to understand admissibility issue.

[@zijunliu7765]

You explained way better than my professor! Thank you! Now I finally understand it.

[@Geek-jx3gw]

throwback 2 years ago, you helped me to pass my exam and understand this algorithm really well

[@balochx]

How's life?

[@Geek-jx3gw]

@@balochx Amazing

[@balochx]

@@Geek-jx3gw stay amazing!

[@Geek-jx3gw]

@@balochx i didnt know what to answer but, life is not organized or as i wanted but it is better now 2 years before I was a stressed person, stressed about a lot of things including my future, grades, etc now, i am older and i changed into a better version of me i guess, less stressed, i love my struggles, i love to help people as much as i can, I’m trying my best to be good enough for me and my family so yeah life is amazing now🙌🏻

[@balochx]

@@Geek-jx3gw thank you so much for sharing. and yes, ups and downs are a part of life. no one is completely satisfied with his/her life, we just have to embrace it and strive for the good. helping people for no agenda brings out huge happiness. and it was nice knowing about your story. I love hearing common people rather than famous people who are faking everything. Stay blessed 🙌

[@SaifUlIslam-di5xv]

It's a treat watching this as an introduction to what A* is. :D

[@coxixx]

the best teacher on the web

[@johnlevine2909]

Thanks. Glad you liked it.

[@abhishekravichandran6965]

kzbin.info/door/M-yUTYGmrNvKOCcAl21g3w she is the best bruh

[@runneypo]

@@abhishekravichandran6965 she has no video on a star though

[@vakiljay8686]

@@abhishekravichandran6965 S I M P

[@heer1359]

@@abhishekravichandran6965 S I M P

[@koibathekingofgames8522]

The best exemplification that I found until now, It`s worth watching.

[@ecekucukpehlivan9779]

These videos are very educational and useful. Thank you so much!

[@kuanghuang2773]

very clear, very smooth, I like the teaching! thanks!

[@faox7565]

what a clean teaching you are the best

[@cieslak4004]

THANK YOU! Greetings from Poland

[@siddarvind6410]

A godsend. This is saving me in my CS Discrete Math class, thank you so much!

[@ShinnyxAKAvincent]

very clear speech, awesome explanation. Thanks a lot!

[@mohammadvasegh1754]

in our country, today is teacher's day good sir. thank you for all of your clarification and examples that you've solved and happy teacher's day to you

[@johnlevine2909]

Thank you Mohamad! I'm really glad you find the videos useful.

[@shreengul6488]

Great job sir!!! You explain things very clearly and unambiguously . No need to watch any other vedio after watching this.

[@willardmakinishi6980]

Thank you so much Mr. Levin. Trust me these things did not make any sense in the first encounter with my Lecturer with due respect to him. I have just watched the first minute and i Have decided to download the tutorial. Hopefully I will find your explanations on all the search Algorithms. God bless you and I hope to understand these things before June for my exams

[@nandudara3845]

This is a perfect video for understanding A* algorithm

[@harpreetset]

really insightful. I am learning AI and have been reading about agent searches for a while. This one is quite helpful. Can you also cover big O notations for time and space for these algorithms? it will help in analyzing in what environments it makes sense to apply them.

[@johnlevine2909]

Thanks. I'm planning to do a video comparing the algorithms, including the time and space requirements, in due course.

[@dushanrathnayake5007]

Just brilliant! Thank you so much! At 5:53 the A* score for A is 17 (5 + 3 +2 + 7) instead of 20 I think.

[@johnlevine2909]

Thank you, and well spotted!

[@piotrptak5507]

Truly the best explanation of this algorithm we can find

[@sibusisondimande5209]

Thanxxxx John. You're the best !!!!!

[@Mousta_alpha94]

thanks Mr john levine your explanation is excellnt

[@AnsumanMohanty]

Clear and concise. But could you share any resource as to why the heuristic should underestimate the cost ?

[@robs939]

John the Goat! Thanks man!

[@maximilianozavala8943]

Amazing explanation, thank you so much!

[@bars5762]

I'm not very good in English but your explaination is very easy to listen and understand. Thank you very much!

[@thinhnguyen3163]

Thank your work, i'm prepairing for AI test next week. Luckily I found this

[@zhenyufan8988]

It's a great illustration!! But can u give us a example of how to decide the estimate value from certain node to a goal node?

[@uchungnguyen1474]

sir hat off for your cleaning teaching!

[@aditisharma8398]

Sir you are the best!

[@baldbadger7644]

the lecture was dilivered in a logical and clear manner, thank you so much

[@grass666]

this tutorial is sooo slay thank you king

[@muinmohammadmozammel281]

Short and to the point explanation. Thanks.

[@alibrahim4686]

You are fantastic. Please make more videos.

[@PierLim]

Thank you for this, it is extremely clear.

[@MuhammadUsman-ry6tp]

One of the best teacher i ever seen

[@iwayanbagus2271]

thank you for your videos! I learnt alot

[@alfianabdulhalin1873]

Thanks John. This video is a lifesaver. BTW, I've a question. Say I want to drive to the nearest city, and he wants to choose between 3 cities on a map (i.e. 3 goals states/nodes). So does this mean I have to calculate the A* score of each goal state, and then choose the smallest one? Thanks!

[@ramiyousif8024]

Best video for Heuristic algorithm!! Thank you !!

[@VaibhavSharma44]

Thank you so much. Tutorials like these are hard to find :)

[@Z3366N]

Thank you for sharing 😊 it was really helpful for me.

[@AshutoshSingh-do4ts]

Thank you sir for the explanation, it helped me a lot to understand the A* algorithm.

[@melihekinci7758]

Very good explanation.. thank you

[@SiEmG]

Hello Mr. John Levine and the rest of the people IN THE COMMENTS :). Mr. Levin thank you very much for your help. You give totally clear instructions!! :) My only question is this: is G node visited also? I think in A* goal state is also added in the visited list, right?

[@muhammadhabib3442]

Great Tutorial, Please also Make another tutorial on the Optimality proof of A∗

[@johnlevine2909]

Many thanks, and thanks for the suggestion - I think that's a great idea.

[@maxharris6926]

Great Video, thank you for explaining A*. For clarification if you find a node that has been visited, but the current path's A* score is less than the cost in the visited set, would you continue on the path and update the A* score in the visited set?

[@message59]

on point 👍🏻 super explanation thank you :)

[@mvvkiran]

So, two points I believe worth mentioning for the General Public's information sake: 1. The Search considered here is a GRAPH Search - NOT a Tree search. John Levine generally considers all Graph Search for all Search Algorithms - at least in the Uninformed & this A* Algs, so far 2. The REASON why the Heuristic MIGHT BE LESS THAN the Actual Cost of Reaching of a Goal is Because the Basic Heuristic considered for an A* Search is a Straight Line Distance - SLD. And we a know a PATH is NOT ALWAYS a Straight Line. How much ever Better a Heuristic you introduce, you'll never get the Actual Cost of Reaching a Goal State to be less than it. The Best Heuristic will Predict the EXACT cost of reaching a Goal State (only with ZERO Path Costs of course as A* Cost = Path Cost + Heuristic Cost) Hope this helps.

[@bamboom9184]

I am serious like wow loved the lecture was soooooo interesting please keep this up you will be helping alot of ppl since most teachers dont know what they are talking about

[@Imhotep1278]

very nice explanation and example, indeed

[@hermosillaignacio]

Awesome video, thank you!

[@OzDavid]

Amazing explanation. thanks sir

[@lancelofjohn6995]

Very good lecture,thanks!

[@aykutyucel7700]

Thanks a lot! You really make it looks easier!

[@johnlevine2909]

Great - glad you found it useful.

[@thugonomicsstark7238]

Dear Professor, this is such an amazing video, your way of explaining is just perfect, however i am doing a path planning for the navigation of a mobile robot in the environment, is A* the best technique to do that ? also, can you link me the litterature for this please ?

[@paulshi2821]

Thank you for explaining this!

[@raiyan22]

thank you! Superb!!

[@kyawnyeinphyo5639]

Sir, thank you for your amazing explanation

[@adeelali8417]

Where do you get the initial node heuristics from or do you estimate them?

[@jamesthuo8763]

Your videos are the best. Please do Greedy and other topics

[@firatyildiz66]

Thank you for the clear explanation sir!

[@Pedrokaz1]

Hope it helps me and my friend on the exam. Thanks for the great tutorial!

[@justafreak15able]

wawo you explained it very simply and quickly.

[@Greatfulone]

Thank you so much for this video. I was looking for an explanation of A*, and I think your video just helped me fix my code and learn why I had to make the change. If I understood your comments, I should only visit a node if I either have not visited it before, or its A* score is lower from the path I am currently considering. And the A* score is a sum of how much it costs to get to a node plus the nodes heuristic value. Is that right?

[@dapengzhang4473]

Really like your video, it is really helpful!!!! Thank you!

[@user-wf8tl6vk9w]

How is the goal state considered in a situation with ties? If using alphabetical order, do goal states count as the alphabet G?

[@cemozen7074]

Did you have to look at E(13) before G(13) ? Since heuristic always underestimates the actual cost, I guess there was no need to expand the E(13) node. However, it was great explanation of A*. Thank you.

[@emrec.4005]

Well, that marvelous.

[@rashidafoodcornervlog654]

Brilliant man you should make more videos

[@flienky]

Does the condition that the heuristic value of a node should be bigger than the distance to the goal, apply to the starting node as well? Or it only applies for the intermediate nodes?

[@ngusumakofu1]

Thank you sir. Made it so much clearer

[@CARELESSuwu]

Brilliant!! Thank you sooo much! :)

[@mobeenahmad4711]

thank you sir it was so clear and concise plz make more tutorials.