Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2 by jasb

View this thread on: hive.blog | peakd.com | ecency.com

blockchain · @jasb · Jun 24 '18 (edited)

$7.67

Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2

<div class="text-justify">
<div class="text-center"><h2>Introduction</h2></div><br>
<p><div class="pull-left"><div class="text-justify">
On the <a href="https://staging.busy.org/@jasb/blockchain-technology-comprehension-a-survey-on-distributed-systems-part-1">previous post</a> the CAP theorem was generally depicted, his consequences where described, and network system designer's strategy to circumvent CAP theorem limitations where briefly summarized.<br>Now we will dig further in the theoretical concepts underlying the CAP theorem. Consistency/Availability trade-offs on partitioned systems will</div></div>
<div class="pull-right"><div class="text-justify">
be shown to be particular cases of the more general Safety/Liveness trade-off in unreliable systems. Then the problem of consensus in distributed systems will be reviewed. Later, we will study what levels of synchrony are required to have both Safety and Liveness, and finally, we will discuss the degree of Consistency that can be achieved in an unreliable system.</div></div>
</p>
<br><br>
<hr>
<div class="text-center"><img src=https://upload.wikimedia.org/wikipedia/commons/thumb/0/08/Blockchain_Illustration_2.jpg/800px-Blockchain_Illustration_2.jpg" alt="Title image"><br>
<sup>Licensed under Creative Commons Attribution-Share Alike 4.0 International license. <a href="https://commons.wikimedia.org/wiki/File:Blockchain_Illustration_2.jpg">Source</a></sup>
<div class="text-center"><img src="https://i.imgur.com/MGhcGai.png" alt="Text divider"></div>
<h2> Safety and Liveness </h2></div>
<hr>
<p>
When executing a program it can run a single isolated set of operations, or it can run several sets simultaneously. Thus, we have sequential programs and concurrent programs. A concurrent program is one in which several streams of operations are executed simultaneously, those streams can communicate and interfere with each other. Those sequences of instructions are called threads, that is why sequential programs are often called <i>single-threaded programs</i></p>
<p>
Even so, any program π can by specified in terms of its sets of atomic actions <b>(A<sub>π</sub>)</b> and a predicate <b>(Init<sub>π</sub>)</b> that describes its possible initial states. An execution of such a program can be thought of as an infinite series of states:</p>
<p>
<div class="text-center">σ = S<sub> 0 </sub>S<sub>1</sub>...<br></div>
</p>
<p>
State  S<sub> 0 </sub> satisfies Init<sub>π</sub>, the program changes its actual state as the result of the application of a single atomic operation from A<sub>π</sub> to the current state. Following this reasoning, we have that a termination execution is one in which an infinite sequence is obtained by repeating the final state. That is, after some finite time we have a constant state on our infinite sequence.
</p>
<p>
Since a Property is a set of sequences of infinite states, and a program also defines a set of such sequences, it is said that a Property <b>"holds"</b> for a program if the set of infinite series of states defined by the program are contained within the Property.</p>
<p>
Now, let <b>S</b> be the set of program states, <b>S<sup> * </sup></b> the finite sequence of program states, and <b>S<sup>w</sup></b> the set of infinite sequences of program states. An execution of the program has to be contain in <b>S<sup>w</sup></b>, thus elements of <b>S<sup>w</sup></b> are also called <i>program executions</i>, and elements of <b>S<sup> * </sup></b> are called <i>partial program executions</i>. When a execution <b>σ</b> is in property <b>P</b> it is denoted as σ|=P, and <b>σ<sub>i</sub></b> are the elements of the partial execution of <b>σ</b> containing the first <b>i</b> elements of execution <b>σ</b>.</p>
<hr>
<h4>Safety</h4>
<p>
For <b>P</b> to be a <i>safety property</i>, if <b>P</b> does not hold for an execution, then at some point some "bad thing" must happen. Thus, P is a <i> safety property </i> if the following holds:</p>
<p>
<div class="text-center">(∀σ: σ ∈ S<sup>w</sup>: σ|≠P ⇒ (∃i: 0 ≤ i: (∀β: β∈ S<sup>w</sup>: σ<sub>i</sub>β |≠P)))<br></div>
</p>
<p>
Then the definition stipulates that if "something bad" does occur, there is some identifiable point <b>i</b> at which it happens.</p>
<hr>
<h4>Liveness</h4>
<p>
For a property <b>P</b> to be a liveness property, we must verify that:<br><br>
</p>
<p>
<div class="text-center">(∀α: α ∈ S<sup> * </sup>: (∃β: β∈ S<sup>w</sup>: αβ|=P))<br></div>
</p>
<p>
A liveness property states that when executing a program eventually the expected outcome does occur.
</p>
<p>
Once we are done considering these concepts, it is clear that Availability is a Liveness property. When we say that we have availability we state that eventually, we will receive a response from the network (something good eventually happens). Also, we can state that Consistency is a Safety property. Remember that we label a system as one with high consistency if the answer obtained from it is always what we were expecting (something bad never happens). 
</p>
<div class="text-center"><img src="https://i.imgur.com/MGhcGai.png" alt="Text divider"></div>
<hr>
<div class="text-center"><h2>Consensus</h2></div><br>
<p>
In an asynchronous system, there are three conditions that must be met in order to reach consensus. First, <b><i>agreement:</i></b> every process must output the same value; <b><i>validity:</i></b> every value output must have been provided as the input for some process; and <b><i>termination:</i></b> eventually, every process must output a value. From the above definitions of, it is clear that agreement and validity both states that for the property to hold, the expected outcome must occur! It is equivalent to stating that for the property to hold no unexpected outcomes occur, thus they are <i>safety</i> properties. Similarly, terminations conditions are clearly those of a liveness property.
</p>
<hr>
<h4>Dealing with the Safety/Liveness trade-off: Synchrony</h4>
<p>
In order to determine what levels of reliability are required to avoid the inherent trade-off between safety and liveness, the degree of synchrony on a network should be analyzed. A synchronous network must have these characteristics: first, all the process within the network has a clock and all the clocks are synchronized; second, messages are delivered within a determined and known amount of time; and third, each process of the networks perform a task at an invariant and known rate. This system can be considered to operate in rounds of repeated and synchronized steps. In those rounds, each process sends some messages, receive the messages sent to them in that round, and perform some individual computation.
</p>
<p>
Consensus requires f + 1 rounds if up to f processes might crash in a synchronous network. In an asynchronous network, consensus is unfeasible if there is only one crash failure. Fortunately, a mean point is usually achieved for real systems. Most real systems reach <i>Eventual Synchrony</i>, it is achieved when a process has some periods of synchrony and some periods of asynchrony, such processes can reach consensus if the synchronous interval lasts long enough. Eventual synchronous system reaches consensus if at least f + 2 rounds are executed within the synchrony interval. Also, crash-fault tolerance is achieved if there are <n/2 crash failures, where "n" is the number of servers.
</p>
<p>
Some other approaches lead to the implementation of an Oracle, this process executes a leader election service and provides sufficient information to reach consensus in an asynchronous crash-prone system. Moreover, there is a perspective focused on establishing the lower reliability levels of linking between the process in the network and the minimal synchrony assumptions to reach consensus in an asynchronous system.
</p>
<hr>
<h4>How consistent a lively, partition-prone network can be?</h4>
<p>
The consensus problem requires that an asynchronous and distributed set of process agree on a common value among themselves. Additionally, this has to be done in the presence of a number of faulty processes and all processes must output some value and terminate.
</p>
<p>
Set-agreement is a "weaker" agreement condition in which process must not agree on a single value but in a set of values. In this condition, each process begins with a certain value v<sub>i</sub> and eventually, every process outputs one of the initial values as the result of an execution. In k-set consensus, each process decides on a single value such that the set of agreed values in any run is of size at must <i>k</i>. K-set agreement can be solved if the number of crash failures is equal or lesser than k-1 and is the higher consistency that can be reached without giving up availability in a system with k-1 failures.
</p>
<hr>
<div class="text-center"><h2>Final Thoughts</h2></div>
<p>
Distributed systems have major theoretical limitations, those limitations have to be dealt ingeniously to achieve the desired levels of reliability in blockchain technology. Major advances have been made from the initials operations with bitcoin to the present times. Several hundreds of projects have implemented subtle variations on consensus algorithms to reach the fittest balance of safety/liveness trade-off for their individual goals. A solid foundation on the theoretical concepts that determine the nature of this trade-off is a key aspect to fully understand the blockchain technology.
</p>
<hr>
<h4>References</h4>
<p>
<ul>
<li>Seth Gilbert and Nancy Lynch. Perspectives on the CAP Theorem. IEEE Computer Society Press, February 2012.</li>
<li> S. Chaudhuri. More choices allow more faults: Set consensus problems in totally asynchronous systems. Information & Computation, 105(1):132–158, 1993</li>
<li>Fischer M, Lynch N, and Paterson N. Impossibility of Distributed Consensus with One Faulty
Process, in "ACM Symposium on Principles of Database Systems". April 1985 </li>
<li>Bowen Alpern and Fred B. Schneider. Recognizing safety and liveness. Distributed Computing September 1987, Volume 2, Issue 3, pp 117–126 </li>
</ul>
</p>
</div>

👍 utopian-io, hendrikdegrote, lafona-miner, steemstem, justtryme90, abigail-dantes, pharesim, bycz, wackou, bue, curie, lemouth, minnowsupport, roelandp, vact, anwenbaumeister, fredrikaa, sbi5, meerkat, anarchyhasnogods, howo, kerriknox, mountain.phil28, mahdiyari, kryzsec, liberosist, thevenusproject, massivevibration, samminator, alexdory, mountainwashere, de-stem, ertwro, gra, zest, benleemusic, lamouthe, saunter, laylahsophia, kenadis, dna-replication, thinknzombie, rharphelle, nitesh9, up-quark, carloserp-2000, croctopus, lianaakobian, ksolymosi, dber, lesshorrible, simplifylife, chloroform, serylt, alexzicky, amavi, fancybrothers, terrylovejoy, foundation, the-devil, alexander.alexis, drmake, mirzantorres, sthephany, and 108 others
👎 hellotomyfans, kipotusong, steemtwitting

`author`	jasb
`permlink`	blockchain-technology-comprehension-a-survey-on-distributed-systems-part-2
`category`	blockchain
`json_metadata`	{"community":"busy","app":"busy/2.4.0","format":"markdown","tags":["blockchain","technology","busy","steemstem"],"users":["jasb"],"links":["https://staging.busy.org/@jasb/blockchain-technology-comprehension-a-survey-on-distributed-systems-part-1","https://commons.wikimedia.org/wiki/File:Blockchain_Illustration_2.jpg"],"image":["https://upload.wikimedia.org/wikipedia/commons/thumb/0/08/Blockchain_Illustration_2.jpg/800px-Blockchain_Illustration_2.jpg","https://i.imgur.com/MGhcGai.png","https://i.imgur.com/MGhcGai.png"]}
`created`	2018-06-23 05:25:51
`last_update`	2018-06-24 15:48:09
`depth`	0
`children`	16
`last_payout`	2018-06-30 05:25:51
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	5.987 HBD
`curator_payout_value`	1.679 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	10,111
`author_reputation`	191,649,551,793
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	0
`post_id`	61,865,038
`net_rshares`	3,852,379,506,521
`author_curate_reward`	""

properties (23)vote details (175)

voter	rshares	pct
wackou	40,560,354,377	0.26%
pharesim	83,104,821,340	0.02%
lafona-miner	213,724,632,574	5%
bue	28,245,110,264	100%
justtryme90	114,000,391,962	5%
anwenbaumeister	15,293,104,907	0.89%
roelandp	19,297,231,102	0.44%
bycz	53,107,765,690	81%
liberosist	3,031,167,715	0.89%
lemouth	26,026,213,923	5%
rjbauer85	314,158,679	5%
anarchyhasnogods	10,442,532,103	3%
lamouthe	1,508,728,506	5%
meerkat	10,646,135,652	0.97%
curie	27,095,568,270	0.89%
hendrikdegrote	522,372,459,310	0.89%
vact	15,869,339,142	0.89%
steemstem	146,136,478,348	5%
foundation	692,806,899	5%
the-devil	657,854,287	5%
thevenusproject	2,819,019,428	5%
dna-replication	1,407,139,379	5%
borislavzlatanov	430,777,429	5%
michelios	589,597,987	0.13%
moksamol	211,259,497	0.44%
jade56	127,090,010	2.5%
kryzsec	3,060,653,741	5%
fredrikaa	13,583,034,782	5%
samminator	2,530,975,820	5%
minnowsupport	23,765,858,709	0.5%
locikll	425,796,305	1.78%
dber	1,043,200,585	5%
mahdiyari	3,209,812,685	2.5%
aboutyourbiz	212,185,869	0.89%
kerriknox	4,203,753,727	5%
alexander.alexis	647,583,296	2%
blessing97	167,088,523	5%
saunter	1,501,798,717	5%
cryptokrieg	253,402,366	0.89%
ertwro	2,075,108,360	5%
juanjdiaz89	57,356,548	5%
thinknzombie	1,349,193,757	0.44%
nitesh9	1,255,422,675	5%
fancybrothers	765,177,509	1.5%
howo	4,889,156,694	2.5%
himal	385,451,605	5%
neumannsalva	115,628,073	0.44%
abigail-dantes	86,130,449,147	5%
suravsingh	66,295,647	5%
planetenamek	130,362,185	0.25%
alexzicky	815,273,265	1.25%
mountain.phil28	3,605,815,384	25%
akeelsingh	209,418,421	5%
mountainwashere	2,228,180,098	5%
zest	1,596,693,230	3.5%
felixrodriguez	152,594,813	2.5%
masterwriter	208,360,679	5%
massivevibration	2,641,656,105	5%
laylahsophia	1,438,699,395	5%
ksolymosi	1,075,106,727	5%
simplifylife	894,820,293	2.5%
mayowadavid	248,611,628	2.5%
zeeshan003	58,273,267	5%
emdesan	426,158,127	10%
happychild	117,377,230	0.44%
peaceandwar	162,259,722	0.44%
enzor	85,478,106	2.5%
pratik27	199,726,040	2.5%
rogeviolinista	119,536,628	10%
carloserp-2000	1,193,463,809	5%
rachelsmantra	214,559,082	5%
gra	1,755,762,371	5%
utopian-io	2,283,560,695,559	1.5%
tfcoates	99,667,218	1.25%
drmake	619,582,813	0.17%
skycae	125,651,314	0.89%
one-person	265,599,069	0.13%
physics.benjamin	103,274,166	5%
kenadis	1,415,751,958	5%
amavi	780,859,306	1%
florae	279,584,232	5%
robotics101	231,118,908	4%
sohailahmed	98,362,349	0.44%
aamin	97,486,966	2.5%
trishy	61,867,531	5%
sco	519,060,482	1%
adetola	407,934,959	5%
anikekirsten	252,988,201	0.89%
rharphelle	1,334,061,340	25%
dysfunctional	276,520,047	2.5%
stahlberg	154,494,375	0.44%
monie	440,947,431	100%
shoganaii	223,784,244	2.5%
mathowl	609,116,861	5%
whileponderin	420,430,020	5%
mittymartz	111,040,512	5%
hadji	203,358,276	5%
sakura1012	202,940,794	5%
terrylovejoy	764,379,813	1.5%
saunter-pl	104,080,174	5%
olajidekehinde	75,197,329	2.5%
steepup	76,144,810	2%
mrday	129,830,449	0.44%
lesshorrible	949,531,597	5%
steem-hikers	94,217,411	5%
kingabesh	154,872,743	2.5%
didic	166,742,415	0.44%
kelos	344,541,112	10%
dexterdev	488,679,383	5%
ugonma	232,683,693	5%
alexdory	2,330,048,816	5%
benleemusic	1,554,645,417	0.08%
lianaakobian	1,081,309,063	4%
croctopus	1,171,039,894	100%
joelagbo	125,182,792	5%
spederson	113,243,367	4.5%
theunlimited	74,696,213	10%
cryptoitaly	240,901,500	2.5%
effofex	176,560,792	2.5%
mrbreeziewrites	271,791,272	5%
de-stem	2,124,821,733	4.5%
serylt	821,291,297	4%
yann85	396,215,538	12%
event-horizon	50,517,276	5%
chloroform	821,877,473	5%
vanessahampton	301,945,810	2.5%
albatar	237,541,864	25%
temitayo-pelumi	313,669,412	5%
doctor-cog-diss	314,350,649	100%
star-vc	134,768,213	5%
golgo-13	50,492,235	9%
chrstnv	609,723,642	100%
sbi5	11,605,594,615	10%
krathos	611,952,180	100%
joelsegovia	597,196,743	100%
sthephany	612,502,409	100%
biomimi	229,444,877	40%
mirzantorres	613,097,409	100%
angelzam	611,587,049	100%
patapa	611,568,962	100%
derg	611,521,760	100%
lagrangemit	611,342,709	100%
riemman-stielmit	611,296,752	100%
astrophoto.kevin	429,913,555	2.5%
kind-sir	64,916,669	2%
call-me-howie	397,885,597	0.44%
sergiotorres	611,015,864	100%
tropicalgrey	611,010,184	100%
hansmast	84,277,209	0.44%
jireneye	610,669,662	100%
maikolp	610,669,662	100%
carlosvls	610,666,615	100%
amelisfer	610,666,615	100%
andypalacios	598,453,282	100%
gatis-photo	66,876,287	2%
sciencebox	610,598,885	100%
scienceboard	610,598,885	100%
jasb	603,197,294	100%
juanchop	610,598,885	100%
karinablanco	598,304,578	100%
vzlauniversity	610,201,134	100%
karlab	610,204,464	100%
masterkey1	610,204,464	100%
michaelto	610,204,464	100%
steemtwitting	0	-100%
changevictory	609,716,763	100%
matrixbinary	609,716,763	100%
fclosamigos	609,716,763	100%
plumesteemit	609,716,763	100%
brandsteemit	609,716,763	100%
parchazar	609,716,763	100%
trickgame	609,716,763	100%
up-quark	1,225,224,808	5%
kipotusong	0	-100%
hellotomyfans	0	-100%

@a-0-0 · Jun 23 '18

Please Upvote➜https://steemit.com/christianity/@bible.com/verse-of-the-day-revelation-21-8-niv

properties (22)

`author`	a-0-0
`permlink`	re-jasb-blockchain-technology-comprehension-a-survey-on-distributed-systems-part-2-20180623t052632794z
`category`	blockchain
`json_metadata`	{"tags":["blockchain"],"links":["https://steemit.com/christianity/@bible.com/verse-of-the-day-revelation-21-8-niv"],"app":"steemit/0.1"}
`created`	2018-06-23 05:26:39
`last_update`	2018-06-23 05:26:39
`depth`	1
`children`	0
`last_payout`	2018-06-30 05:26:39
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	94
`author_reputation`	-4,863,186,238,920
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	61,865,107
`net_rshares`	0

@minnowsupport · Jun 23 '18

<p>Congratulations!  This post has been upvoted from the communal account, @minnowsupport, by jasb from the Minnow Support Project. It's a witness project run by aggroed, ausbitbank, teamsteem, theprophet0, someguy123, neoxian, followbtcnews, and netuoso. The goal is to help Steemit grow by supporting Minnows.  Please find us at the <a href="https://discord.gg/HYj4yvw"> Peace, Abundance, and Liberty Network (PALnet) Discord Channel</a>.  It's a completely public and open space to all members of the Steemit community who voluntarily choose to be there.</p> <p>If you would like to delegate to the Minnow Support Project you can do so by clicking on the following links: <a href="https://v2.steemconnect.com/sign/delegateVestingShares?delegator=&amp;delegatee=minnowsupport&amp;vesting_shares=102530.639667%20VESTS">50SP</a>, <a href="https://v2.steemconnect.com/sign/delegateVestingShares?delegator=&amp;delegatee=minnowsupport&amp;vesting_shares=205303.639667%20VESTS">100SP</a>, <a href="https://v2.steemconnect.com/sign/delegateVestingShares?delegator=&amp;delegatee=minnowsupport&amp;vesting_shares=514303.639667%20VESTS">250SP</a>, <a href="https://v2.steemconnect.com/sign/delegateVestingShares?delegator=&amp;delegatee=minnowsupport&amp;vesting_shares=1025303.639667%20VESTS">500SP</a>, <a href="https://v2.steemconnect.com/sign/delegateVestingShares?delegator=&amp;delegatee=minnowsupport&amp;vesting_shares=2053030.639667%20VESTS">1000SP</a>, <a href="https://v2.steemconnect.com/sign/delegateVestingShares?delegator=&amp;delegatee=minnowsupport&amp;vesting_shares=10253030.639667%20VESTS">5000SP</a>. <br><strong>Be sure to leave at least 50SP undelegated on your account.</strong></p>

properties (22)

`author`	minnowsupport
`permlink`	re-blockchain-technology-comprehension-a-survey-on-distributed-systems-part-2-20180623t054913z
`category`	blockchain
`json_metadata`	"{"app": "beem/0.19.38"}"
`created`	2018-06-23 05:49:12
`last_update`	2018-06-23 05:49:12
`depth`	1
`children`	0
`last_payout`	2018-06-30 05:49:12
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	1,700
`author_reputation`	148,902,805,319,183
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	61,867,108
`net_rshares`	0

@plumesteemit · Jun 24 '18

Hello everyone, well I was reading your post @jasb and the comments too by @riemman-stielmit, well, I remember that importance of meeting the difference between Threads and Processes. If you want to programme a network you need to know what it will the resources (hardware) and the users that will use your network, why? because the threads are the lifejacket when your processing power is slow, and if the amount of user arrive faster than your machine can treat, you'll need implement threads indeed.

The Processes need more capacity of the hardware if you want to use in a light network, is easiest than Thread to implement, if you do something wrong only reach the process. Don't even think about the Threads (lol). 

Well, @jasb when you refer to safety and liveness networks, do you only have in mind threads?

What is the central idea in Synchrony (Dealing with the Safety/Liveness trade-off)? It was confusing to me. 

I'll expect your answers, see u

<center>@plumesteemit</center>
<center> ![separadorplumesteemit.png](https://cdn.steemitimages.com/DQmVCL7Z29YTPbJNBQnge3Erw32G6nx2mywSZydY8bb2Eej/separadorplumesteemit.png)</center>

properties (22)

`author`	plumesteemit
`permlink`	re-jasb-blockchain-technology-comprehension-a-survey-on-distributed-systems-part-2-20180624t222243053z
`category`	blockchain
`json_metadata`	{"tags":["blockchain"],"users":["jasb","riemman-stielmit","plumesteemit"],"image":["https://cdn.steemitimages.com/DQmVCL7Z29YTPbJNBQnge3Erw32G6nx2mywSZydY8bb2Eej/separadorplumesteemit.png"],"app":"steemit/0.1"}
`created`	2018-06-24 22:22:45
`last_update`	2018-06-24 22:22:45
`depth`	1
`children`	0
`last_payout`	2018-07-01 22:22:45
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	1,143
`author_reputation`	29,469,732,579
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	62,105,976
`net_rshares`	0

@riemman-stielmit · Jun 24 '18

Hey bro! It's nice to know you are serious with this project, I really liked your post.
There is something that's not clear to me, you define concurrent programs as a multiple thread program. I imagine that like many programs executing itselves and interacting with each other, but if that's so, then you can count the states of a concurrent program as the sum of several sequential program states. Since sequential programs have a finite set of states then the sum of the states of a finite set of sequential programs is finite. But then why concurrent programs have infinite states, that's my doubt

properties (22)

`author`	riemman-stielmit
`permlink`	re-jasb-blockchain-technology-comprehension-a-survey-on-distributed-systems-part-2-20180624t141104127z
`category`	blockchain
`json_metadata`	{"tags":["blockchain"],"app":"steemit/0.1"}
`created`	2018-06-24 14:11:39
`last_update`	2018-06-24 14:11:39
`depth`	1
`children`	1
`last_payout`	2018-07-01 14:11:39
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	600
`author_reputation`	2,459,880,824
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	62,051,306
`net_rshares`	0

@jasb · Jun 24 '18 (edited)

<div class="text-justify">
<i>I'm happy to know that you liked the post.</i><br><br>
 Ok, let's clarify it a little bit.
<ol>
<li>The threads are series of instructions (a.k.a. statements) executed when running a program. The state is the current situation of the variables stored in memory by the program.</li>
<li>A program can be <b>determined</b> by the set of operations allowed for that particular program and its initial state (much like how you determine the position of a body at any time if you know the position at <b>t<sub>0</sub></b> and the explicit expression of the function <b>V(t)</b> in classical mechanics).</li>
<li>Changes on states of a program are the result of applying an atomic operation from (A<sub>π</sub>) to the previous state. For the initial execution the first operation is made on the initial state, then the second operation is executed over the result of the first operation and so on.</li>
<li><b>The execution of any program (not just concurrent ones)</b> can be thought of as a infinite series of states. Even if a program state is constant, it can be represented as an infinite series of the initial state σ = S<sub>0</sub>S<sub>0</sub>S<sub>0</sub>...<br>
So there is no such a finite series for a sequential program for a given execution. What do exist is a finite sequence <b>for a partial execution of a program</b>, this fact does not change if the program is sequential or concurrent.
</li>
</ol><br>
I hope I have given a clearer explanation. If you have more questions make more comments without doubt.<br><br>
cya.
</div>

properties (22)

`author`	jasb
`permlink`	re-riemman-stielmit-re-jasb-blockchain-technology-comprehension-a-survey-on-distributed-systems-part-2-20180624t170316494z
`category`	blockchain
`json_metadata`	{"tags":["blockchain"],"community":"busy","app":"busy/2.4.0"}
`created`	2018-06-24 17:03:30
`last_update`	2018-06-24 17:05:48
`depth`	2
`children`	0
`last_payout`	2018-07-01 17:03:30
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	1,571
`author_reputation`	191,649,551,793
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	62,072,297
`net_rshares`	0

@steemitboard · Jun 30 '18

Congratulations @jasb! You have completed some achievement on Steemit and have been rewarded with new badge(s) :

[![](https://steemitimages.com/70x70/http://steemitboard.com/notifications/firstpayout.png)](http://steemitboard.com/@jasb) You got your First payout

<sub>_Click on the badge to view your Board of Honor._</sub>
<sub>_If you no longer want to receive notifications, reply to this comment with the word_ `STOP`</sub>



**Do not miss the [last post](https://steemit.com/steemitboard/@steemitboard/steemitboard-world-cup-contest-uruguay-vs-portugal) from @steemitboard!**

---
**Participate in the [SteemitBoard World Cup Contest](https://steemit.com/steemitboard/@steemitboard/steemitboard-world-cup-contest-collect-badges-and-win-free-sbd)!**
Collect World Cup badges and win free SBD
Support the Gold Sponsors of the contest: [@good-karma](https://v2.steemconnect.com/sign/account-witness-vote?witness=good-karma&approve=1) and [@lukestokes](https://v2.steemconnect.com/sign/account-witness-vote?witness=lukestokes.mhth&approve=1)

---

> Do you like [SteemitBoard's project](https://steemit.com/@steemitboard)? Then **[Vote for its witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1)** and **get one more award**!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20180630t102048000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2018-06-30 10:20:48
`last_update`	2018-06-30 10:20:48
`depth`	1
`children`	0
`last_payout`	2018-07-07 10:20:48
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	1,272
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	62,853,135
`net_rshares`	0

@steemitboard · Jun 30 '18

Congratulations @jasb! You have completed some achievement on Steemit and have been rewarded with new badge(s) :

[![](https://steemitimages.com/70x80/http://steemitboard.com/notifications/votes.png)](http://steemitboard.com/@jasb) Award for the number of upvotes

<sub>_Click on the badge to view your Board of Honor._</sub>
<sub>_If you no longer want to receive notifications, reply to this comment with the word_ `STOP`</sub>



**Do not miss the [last post](https://steemit.com/steemitboard/@steemitboard/steemitboard-world-cup-contest-croatia-vs-denmark) from @steemitboard!**

---
**Participate in the [SteemitBoard World Cup Contest](https://steemit.com/steemitboard/@steemitboard/steemitboard-world-cup-contest-collect-badges-and-win-free-sbd)!**
Collect World Cup badges and win free SBD
Support the Gold Sponsors of the contest: [@good-karma](https://v2.steemconnect.com/sign/account-witness-vote?witness=good-karma&approve=1) and [@lukestokes](https://v2.steemconnect.com/sign/account-witness-vote?witness=lukestokes.mhth&approve=1)

---

> Do you like [SteemitBoard's project](https://steemit.com/@steemitboard)? Then **[Vote for its witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1)** and **get one more award**!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20180630t223353000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2018-06-30 22:33:51
`last_update`	2018-06-30 22:33:51
`depth`	1
`children`	0
`last_payout`	2018-07-07 22:33:51
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	1,271
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	62,922,997
`net_rshares`	0

@steemitboard · Jul 6 '18

Congratulations @jasb! You have completed the following achievement on Steemit and have been rewarded with new badge(s) :

[![](https://steemitimages.com/70x80/http://steemitboard.com/notifications/votes.png)](http://steemitboard.com/@jasb) Award for the number of upvotes

<sub>_Click on the badge to view your Board of Honor._</sub>
<sub>_If you no longer want to receive notifications, reply to this comment with the word_ `STOP`</sub>



**Do not miss the last post from @steemitboard:**
[SteemitBoard World Cup Contest - Brazil vs Belgium](https://steemit.com/steemitboard/@steemitboard/steemitboard-world-cup-contest-brazil-vs-belgium)

---
**Participate in the [SteemitBoard World Cup Contest](https://steemit.com/steemitboard/@steemitboard/steemitboard-world-cup-contest-collect-badges-and-win-free-sbd)!**
Collect World Cup badges and win free SBD
Support the Gold Sponsors of the contest: [@good-karma](https://v2.steemconnect.com/sign/account-witness-vote?witness=good-karma&approve=1) and [@lukestokes](https://v2.steemconnect.com/sign/account-witness-vote?witness=lukestokes.mhth&approve=1)

---

> Do you like [SteemitBoard's project](https://steemit.com/@steemitboard)? Then **[Vote for its witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1)** and **get one more award**!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20180706t010329000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2018-07-06 01:03:27
`last_update`	2018-07-06 01:03:27
`depth`	1
`children`	0
`last_payout`	2018-07-13 01:03:27
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	1,330
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	63,592,181
`net_rshares`	0

@steemitboard · Aug 4 '18

Congratulations @jasb! You have completed the following achievement on Steemit and have been rewarded with new badge(s) :

[![](https://steemitimages.com/70x80/http://steemitboard.com/notifications/votes.png)](http://steemitboard.com/@jasb) Award for the number of upvotes

<sub>_Click on the badge to view your Board of Honor._</sub>
<sub>_If you no longer want to receive notifications, reply to this comment with the word_ `STOP`</sub>



> Do you like [SteemitBoard's project](https://steemit.com/@steemitboard)? Then **[Vote for its witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1)** and **get one more award**!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20180804t090850000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2018-08-04 09:08:51
`last_update`	2018-08-04 09:08:51
`depth`	1
`children`	0
`last_payout`	2018-08-11 09:08:51
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	662
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	67,073,207
`net_rshares`	0

@steemitboard · Aug 17 '18

Congratulations @jasb! You have completed the following achievement on Steemit and have been rewarded with new badge(s) :

[![](https://steemitimages.com/70x80/http://steemitboard.com/notifications/votes.png)](http://steemitboard.com/@jasb) Award for the number of upvotes

<sub>_Click on the badge to view your Board of Honor._</sub>
<sub>_If you no longer want to receive notifications, reply to this comment with the word_ `STOP`</sub>



> Do you like [SteemitBoard's project](https://steemit.com/@steemitboard)? Then **[Vote for its witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1)** and **get one more award**!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20180817t075235000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2018-08-17 07:52:33
`last_update`	2018-08-17 07:52:33
`depth`	1
`children`	0
`last_payout`	2018-08-24 07:52:33
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	662
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	68,473,611
`net_rshares`	0

@steemitboard · Aug 30 '18

Congratulations @jasb! You have completed the following achievement on Steemit and have been rewarded with new badge(s) :

[![](https://steemitimages.com/70x80/http://steemitboard.com/notifications/votes.png)](http://steemitboard.com/@jasb) Award for the number of upvotes

<sub>_Click on the badge to view your Board of Honor._</sub>
<sub>_If you no longer want to receive notifications, reply to this comment with the word_ `STOP`</sub>



> Do you like [SteemitBoard's project](https://steemit.com/@steemitboard)? Then **[Vote for its witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1)** and **get one more award**!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20180830t000811000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2018-08-30 00:08:12
`last_update`	2018-08-30 00:08:12
`depth`	1
`children`	0
`last_payout`	2018-09-06 00:08:12
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	662
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	69,745,637
`net_rshares`	0

@steemitboard · Sep 16 '18

Congratulations @jasb! You have completed the following achievement on the Steem blockchain and have been rewarded with new badge(s) :

[![](https://steemitimages.com/70x80/http://steemitboard.com/notifications/votes.png)](http://steemitboard.com/@jasb) Award for the number of upvotes

<sub>_Click on the badge to view your Board of Honor._</sub>
<sub>_If you no longer want to receive notifications, reply to this comment with the word_ `STOP`</sub>



> Support [SteemitBoard's project](https://steemit.com/@steemitboard)! **[Vote for its witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1)** and **get one more award**!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20180916t013120000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2018-09-16 01:31:21
`last_update`	2018-09-16 01:31:21
`depth`	1
`children`	0
`last_payout`	2018-09-23 01:31:21
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	666
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	71,406,837
`net_rshares`	0

@steemitboard · Nov 14 '18

Congratulations @jasb! You have completed the following achievement on the Steem blockchain and have been rewarded with new badge(s) :

<table><tr><td>https://steemitimages.com/60x70/http://steemitboard.com/@jasb/votes.png?201811141518</td><td>You made more than 3000 upvotes. Your next target is to reach 4000 upvotes.</td></tr>
</table>

<sub>_[Click here to view your Board of Honor](https://steemitboard.com/@jasb)_</sub>
<sub>_If you no longer want to receive notifications, reply to this comment with the word_ `STOP`</sub>



**Do not miss the last post from @steemitboard:**
<table><tr><td><a href="https://steemit.com/steemfest/@steemitboard/the-meet-the-steemians-contest-is-over-results-are-coming-soon"><img src="https://steemitimages.com/64x128/https://cdn.steemitimages.com/DQmeLukvNFRsa7RURqsFpiLGEZZD49MiU52JtWmjS5S2wtW/image.png"></a></td><td><a href="https://steemit.com/steemfest/@steemitboard/the-meet-the-steemians-contest-is-over-results-are-coming-soon">The Meet the Steemians Contest is over - Results are coming soon ...</a></td></tr></table>

> Support [SteemitBoard's project](https://steemit.com/@steemitboard)! **[Vote for its witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1)** and **get one more award**!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20181114t173211000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2018-11-14 17:32:09
`last_update`	2018-11-14 17:32:09
`depth`	1
`children`	0
`last_payout`	2018-11-21 17:32:09
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	1,280
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	75,287,361
`net_rshares`	0

@steemitboard · Mar 12 '19

Congratulations @jasb! You received a personal award!

<table><tr><td>https://steemitimages.com/70x70/http://steemitboard.com/@jasb/dw-early.png</td><td>DrugWars Early Access<br>Thank you for taking part in the early access of Drugwars.</td></tr></table>

<sub>_You can view [your badges on your Steem Board](https://steemitboard.com/@jasb) and compare to others on the [Steem Ranking](http://steemitboard.com/ranking/index.php?name=jasb)_</sub>


**Do not miss the last post from @steemitboard:**
<table><tr><td><a href="https://steemit.com/drugwars/@steemitboard/drugwars-early-adopter"><img src="https://steemitimages.com/64x128/https://cdn.steemitimages.com/DQmYGN7R653u4hDFyq1hM7iuhr2bdAP1v2ApACDNtecJAZ5/image.png"></a></td><td><a href="https://steemit.com/drugwars/@steemitboard/drugwars-early-adopter">Are you a DrugWars early adopter? Benvenuto in famiglia!</a></td></tr></table>

###### [Vote for @Steemitboard as a witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1) to get one more award and increased upvotes!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20190312t215844000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2019-03-12 21:58:45
`last_update`	2019-03-12 21:58:45
`depth`	1
`children`	0
`last_payout`	2019-03-19 21:58:45
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	1,065
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	81,173,579
`net_rshares`	0

@steemitboard · May 12 '19

Congratulations @jasb! You received a personal award!

<table><tr><td>https://steemitimages.com/70x70/http://steemitboard.com/@jasb/birthday1.png</td><td>Happy Birthday! - You are on the Steem blockchain for 1 year!</td></tr></table>

<sub>_You can view [your badges on your Steem Board](https://steemitboard.com/@jasb) and compare to others on the [Steem Ranking](http://steemitboard.com/ranking/index.php?name=jasb)_</sub>


**Do not miss the last post from @steemitboard:**
<table><tr><td><a href="https://steemit.com/steemitboard/@steemitboard/steemitboard-witness-update-2019-05"><img src="https://steemitimages.com/64x128/http://i.cubeupload.com/7CiQEO.png"></a></td><td><a href="https://steemit.com/steemitboard/@steemitboard/steemitboard-witness-update-2019-05">SteemitBoard - Witness Update</a></td></tr></table>

###### [Vote for @Steemitboard as a witness](https://v2.steemconnect.com/sign/account-witness-vote?witness=steemitboard&approve=1) to get one more award and increased upvotes!

properties (22)

`author`	steemitboard
`permlink`	steemitboard-notify-jasb-20190512t041011000z
`category`	blockchain
`json_metadata`	{"image":["https://steemitboard.com/img/notify.png"]}
`created`	2019-05-12 04:10:12
`last_update`	2019-05-12 04:10:12
`depth`	1
`children`	0
`last_payout`	2019-05-19 04:10:12
`cashout_time`	1969-12-31 23:59:59
`total_payout_value`	0.000 HBD
`curator_payout_value`	0.000 HBD
`pending_payout_value`	0.000 HBD
`promoted`	0.000 HBD
`body_length`	998
`author_reputation`	38,975,615,169,260
`root_title`	"Blockchain Technology Comprehension. A Survey On Distributed Systems -Part 2"
`beneficiaries`	`[]`
`max_accepted_payout`	1,000,000.000 HBD
`percent_hbd`	10,000
`post_id`	84,699,203
`net_rshares`	0

@utopian-io · Jun 24 '18

#### Hi @jasb!

Your post was upvoted by utopian.io in cooperation with steemstem - supporting knowledge, innovation and technological advancement on the Steem Blockchain.

#### Contribute to Open Source with utopian.io
Learn how to contribute on <a href="https://join.utopian.io">our website</a> and join the new open source economy.

**Want to chat? Join the Utopian Community on Discord https://discord.gg/h52nFrV**

properties (22)