japanese term riai and his meaning in judo

I found Riai term in Ishikawa/Draeger book about Randori no kata at first. In the first part of book are more explanation from Kodokan high ranking senseis, top japanese judokas about importance and benefits of Nage-no-kata, Katame-no-kata practice. The word riai is there very often used.

Isikawa/Draeger translate riai as synergy in short.

Next I read about term riai in judo if from 2016 New year speech of Kodokan president Uemura. He wrote:
Most of participants were gripping each other well and showed their offensive and defensive techniques during exciting matches. However, still there were some players who were disregarding Riai (the principle of using correct, sufficient motion to perform each technique properly with maximum efficiency) such as Kuzushi, Tsukuri and Kake. Watching such players who were repeating false attacks, I realized the importance of having players understand the Riai of Judo through player development. During the competition, Japanese players attracted many audiences by their approach always aiming at Ippon and by their attitude keeping calm whether they won or not. Concerning the refereeing,
...
Not only that, I would like the participants to understand correctly Riai, the original principle of the techniques in Judo and the meaning to control the opponent in this seminar as well.

My understanding is meaningful equivalent reaction in situation kata, randori, shiai. meaningful equivalent = with maximum efficiency

How do you understand what Riai mean?

https://classicbudoka.wordpress.com/2011/11/10/40-riai-the-meaning-of-the-meaning/

Thanks to Jonsey for that interesting link.

An old All Japan Judo Federation article includes a partial explanation of riai to include:
理合 .... riai - 'underlying principles' is as good a definition as any and better than most
正確度 - seikakudo - degree of precision
技の要点 - waza no yôten - the gist of the technique
順序 - junjo - sequence
緩急 - kankyû - pacing
強弱 - strength and weakness / strength
タイミング - timing
リゼム - rhythm
等 - etc

So, in short, your examples don't seem so correct.

Noboru got me curious, and I reread all the sections of Draeger that mention riai.

It's sort of all over the map, not only in what Draeger said, but also because he quotes a number of senior Japanese judoka, but most do not attempt to explain the term. Major Draeger did not speak or read Japanese very well, so surely there was a lot of pain and miscommunication in his research. Also, often many of these terms simply don't translate simply and succinctly because the Japanese themselves haven't pinned down a clear definition.

Pg 43
'... the performance of appropriate action (riai)...'

pg 79-80
'.... riai, or the correct use of Uke's attack strength in the management of Tori's body as he responds in defense and climaxes his actions by a throwing technique against Uke.'

pg 419
'2. The riai (synergy). Some experts believe this the most important lesson that is to be learned in kata. Closely related to engagement distance, the riai stands as the Principle of Judo in action. Both yielding and resisting are employed by Tori and Uke to dominate the other by retaining the attack initiative. The riai includes the correct way to meet your Uke's strength, to blend your strength with his, to control his strength, and finally, to subdue him by the application of an appropriate throwing action. ...'

Synergy was a new term when Draeger wrote his book, and it may have made sense at the time, but I think there are many better ways to describe riai. Perhaps he meant there is a synergy of many different elements that make up riai.

Kawamura and Daigo talk about riai as being the underlying principle or theory of an art. In judo this includes avoiding attempting to control an opponent by using power, in favour of throwing him/her through skilful balance breaking (kuzushi) body shifting (tai-sabaki) and other techniques that use energy and movement in the most efficient, elegant way possible (seiryoku zenyo).

I just don't see the difficulties with "ri ai"

ri = principle
ai = unite, blend

riai = to unite/blend with the principles (of Judo)

Principles of Judo are:

seiryoku zenyo (mind/body = energies best use)

jita kyoei (me und you glory together = mutual welfare and benefit)

ju (soft, flexible, pliant, yielding)

do (way as a physical, moral, social, intellectual education, shin-gi-tai, shu-ha-ri)

A person (ka) who meets/blend with (ai) the principles (ri) of Ju(flexible,soft) do (way) ,

is a Ju-do-ka.

As I said above....