A few days ago i gave a talk on Reinforcement learning with a focus on Qlearning at Cookpads Tokyo office. https://www.meetup.com/tokyomachinelearningkitchen/events/242060161/
The main slides for the talk are here https://github.com/ashleysmart/mlgym/blob/master/qlearning/main_slides.html
I have been neglecting my blog lately so i figured i would convert the slides into a post so lets get started.
The Q function is a estimate of the systems potential value. It is accessed based on:
 The environment or state that the system is in
 The actions that can be taken from that state
 The rewards that can be acquired by performing the action
Q'(s_t, a_t)=Q(s_t,a_t)+\alpha\Big(r_t+\gamma\max_{a}Q(s_{t+1},a)Q(s_t,a_t)\Big)

Q
: The function that guess the total 'value' of rewards

Q
: The new iteration of the 'value'

s_t
: The “State” of the environment at time 't'

a_t
: The “action” perform at time 't'

r_t
: The “reward” received for the action at 't'

s_{t+1}
: The “State” of the environment after action at time 't'

a
: A possible action performed from state 't+1'

\alpha
: The learning rate, how quickly to adjust when wrong. This limited between 0 and 1

\gamma
: The discount rate, how important/trusted future rewards are. This limited between 0 and 1. and has a effect that can be considered as a EMA(exponential moving average)
Q'(s_t, a_t)=Q(s_t,a_t)+\alpha\Big(r_t+\gamma\max_{a}Q(s_{t+1},a)Q(s_t,a_t)\Big)
Q'(s_t, a_t)is in several places so we can group it together..
Q'(s_t, a_t)=(1\alpha)Q(s_t, a_t)+\alpha\Big(r_t+\gamma\max_{a}Q(s_{t+1}, a)\Big)
Q_{target}=r_t+\gamma\max_{a}Q(s_{t+1}, a)
Q_{new}=(1\alpha)Q_{target}+\alpha Q_{target}
Q_{target} \approx Q_{current} \approx Q_{new}
Q_{final} \approx Q_{target} = r_t+\gamma\max_{a} Q(s_{t+1},a)
"Q_{new}=(1\alpha)Q_{current}+\alpha Q_{update}
 The forumla is iterative
 The is top down
Q_{update}=r_t+\gamma\max_{a}Q(s_{t+1}, a)
 This is the *local* best not the *global*
 It is a heuristic know in computer science as Greedy Optimization." },