Question about the maths behind attack roll and defense rolls

[laguna]

Originally Posted by Landwalker

Why would you expect two master swordsmen to rapidly dismember each other instead of to have a long, drawn-out duel?

i wouldn't expect them to, but under my previous understanding of the rules, I would PREFER they chop each other up quickly as opposed to having a net 5% chance to hit per turn.

[Landwalker]

Originally Posted by laguna

i wouldn't expect them to, but under my previous understanding of the rules, I would PREFER they chop each other up quickly as opposed to having a net 5% chance to hit per turn.

So, as I understand it, you want them to dismember each other because it's quicker and more convenient for you, as opposed to adhering to realistic expectations?

(I'm not saying there's anything wrong with wanting convenience, I'm just verifying what your position is.)

And in any case, even if you bump them up to Skill 26, the 5% hit chance is hyperbolic.

Skill 26 means Parry 16 (and what the heck, let's give them Combat Reflexes and Enhanced Parry 1, for a Parry of 18).

The attacker can take a -16/-8 Deceptive Attack, dropping both the attack and the parry to Effective Skill 10, and there would be a 25% chance of successfully striking the defender.

A -14/-7 deceptive attack: 27.8%

-12/-6: 24.4%

So the -14/-7 is the optimal point, giving you a 27.8% chance of success per turn.

If you adhere to the "one-second turn" idea, then that means that there will be about one strike per four seconds per swordsman. It's not unreasonable, then, that such an encounter might last 15 seconds or less.

That's also disregarding other attack options. If the attacker uses a Committed Attack (Determined), he can get up to 37.1% with a -16/-8 Deceptive Attack, but he'll be in a bad spot defending afterwards.

And then of course there are Feints (and Beats and Ruses), dozens of techniques, rapid strikes, etc.

[DukeofDellot]

Right... okay, I forgot the formula... ungh... I think, and I hope I got it right this time, it's...

(((Chance to hit)-(Crit Chance))*(Chance to fail Active defense))+(Chance to Crit)

And when you have combat reflexes, you have probably within 5% of one out of three chance to hit the target... sorry I got things backwards.

The idea is that two master swordsman attacking each other several times before first blood may seem unattractive to some... if it is, you can always fast-draw first if you havethe higher speed and slice the guy with a deceptive All-Out Attack (Double) and get him before he does anything... I mean that's what I'd do if I was put into the situation... unless he already has his blade ready, then I would throw something and run, hide behind the corner and get him when his back is turned... or something else delightfully cheesy.

If you want it to take longer, take enhanced block, a shield, and wear the heaviest armor you can afford... and this just skims the surface...

...and I'm way off topic by now.

[laguna]

@landwalker you are correct, i am willing to sacrifice realism for (in this case) game flow. but as i said, i didn't understand the significance of deceptive attack so this particular fudging won't be necessary when my game starts.

[gjc8]

Originally Posted by Landwalker

And in any case, even if you bump them up to Skill 26, the 5% hit chance is hyperbolic.

The 5% hit chance was before I drew his attention to Deceptive Attack.

[Dragondog]

This is what it means.

The first table has the percentages as they stand today. The second table has the percentages if you use the quick contest rules.

In quick contest, the only thing that matters is the difference between the stats that are compared, so the listed a margin is the difference between attack and defense. And it shows the percentages of how often the character with the higest stat will win.

	Attack											
Defense	5	            6	            7	            8	            9	           10	            11	            12	          13	          14	          15	         16
5	4,501028807	8,916323731	15,53926612	24,81138546	35,84962277	47,77091907	59,69221536	70,73045267	80,00257202	86,6255144	91,16941015	94,03292181
6	4,372427984	8,573388203	14,87482853	23,69684499	34,19924554	45,54183813	56,88443073	67,38683128	76,20884774	82,51028807	86,96844993	89,91769547
7	4,179526749	8,058984911	13,87817215	22,02503429	31,7236797	42,19821674	52,67275377	62,37139918	70,51826132	76,33744856	80,6670096	83,74485597
8	3,909465021	7,338820302	12,48285322	19,68449931	28,25788752	37,51714678	46,77640604	55,34979424	62,55144033	67,69547325	71,84499314	75,10288066
9	3,587962963	6,481481481	10,82175926	16,89814815	24,13194444	31,94444444	39,75694444	46,99074074	53,06712963	57,40740741	61,34259259	64,81481481
10	3,240740741	5,555555556	9,027777778	13,88888889	19,67592593	25,92592593	32,17592593	37,96296296	42,82407407	46,2962963	50	        53,7037037
11	2,893518519	4,62962963	7,233796296	10,87962963	15,21990741	19,90740741	24,59490741	28,93518519	32,58101852	35,18518519	38,65740741	42,59259259
12	2,572016461	3,772290809	5,572702332	8,093278464	11,09396433	14,33470508	17,57544582	20,57613169	23,09670782	24,89711934	28,15500686	32,30452675
13	2,301954733	3,0521262	4,177383402	5,752743484	7,628172154	9,653635117	11,67909808	13,55452675	15,12988683	16,25514403	19,3329904	23,66255144
14	2,109053498	2,537722908	3,180727023	4,080932785	5,15260631	6,310013717	7,467421125	8,53909465	9,439300412	10,08230453	13,03155007	17,48971193
15	1,980452675	2,19478738	2,516289438	2,966392318	3,502229081	4,080932785	4,659636488	5,195473251	5,645576132	5,967078189	8,830589849	13,3744856
16	1,903292181	1,989026063	2,117626886	2,297668038	2,512002743	2,743484225	2,974965706	3,189300412	3,369341564	3,497942387	6,310013717	10,90534979

Margin	High Wins
0	45,35751029
1	54,64248971
2	63,68955761
3	72,06147119
4	79,41529492
5	85,5366941
6	90,35279492
7	93,92361111
8	96,41203704
9	98,03240741
10	99,00977366

[Nymdok]

Originally Posted by DukeofDellot

(((Chance to hit)-(Crit Chance))*(Chance to fail Active defense))+(Chance to Crit)

Yup thats it but it gets more comlicated quickly!

I jsut finished my first few web pages on the subject (Check my sig). I even have a google spreadsheet dedicated to the cause.

(Chance of a Crit) + (Chance of a Hit thats not a Crit)(Chance of Failed Defense)

there is also the matter of how likely you are to penetrate armor. (The odds your DMG exceeds theri DR).

Its all under the GURPS and game Balance link.

Nymdok

[SolemnGolem]

Originally Posted by Landwalker

Why would you expect two master swordsmen to rapidly dismember each other instead of to have a long, drawn-out duel?

This could be quite accurate though. Skill improves, but in GURPS your hit points don't. And as a fighter becomes more and more effective at doing high damage, the human biology doesn't keep pace with the ability to absorb damage (no matter what DnD and its 100+ HP characters would have you believe).

This may not apply to all fighting styles, but I'd say it's an accurate model for several. In fencing matches it's been my experience and observation that mid-level fencers give the most "entertaining" matches. The high-level fencers strike so quickly that one or the other has blown through to their target in a handful of seconds. (Granted, this is under competition-safety conditions where the round is over upon a successful hit - but I can only imagine the real-life swordfight experience wouldn't be much different. Once you start taking damage, you're into the vicious cycle of injuries hampering performance, leading to more injuries.)

[DouglasCole]

Originally Posted by Landwalker

Why would you expect two master swordsmen to rapidly dismember each other instead of to have a long, drawn-out duel?

When I've seen two master martial artists fight, I don't notice that bouts go on longer. If anything, they're shorter than novice v novice fights (the novices spend a lot of time moving around doing utterly ineffective things).

Turning my observations to GURPS, what I've seen is that good practitioners basically throw Deceptive attacks that bring their hit chance down to a net of 13-14 as a matter of course (after footing, which is almost always good, and hit location and use of Techniques are accounted for). You throw the bestest blow you can without flailing, and you do it every time it matters.

The only time you don't do this is when you're using lower skill than you have in order to teach...

[Fred Brackin]

Originally Posted by Landwalker

And in any case, even if you bump them up to Skill 26, the 5% hit chance is hyperbolic.

If you're talking about Critical Hits that goes to 6 or less at Skill 16 or approx. 10%.

To use the numbers from Basic Critical hits go from 1.9% at 14 or less to 4.6% at 15 to 9.3% at 16. Skill 16 also drops Crit Fails from 17-18 to just 18.

So the chance of getting in that fight-ender more than double by going from 14 to 15 and double again from 15 to 16. The chance of spazzing out goes down by a factor of 4 too. That's actually a very sharp delineation in "real" Skill levels.

So fights between masters really might be shorter.