I want Natsuki to notify me when she goes down. This task is harder than I have thought. How can I count on a failing bot to send a message? I cannot trust the hosting provider, either. They may be the reason why the bot goes down. I have to rely on a third party.

#[shuttle_runtime::async_trait]
impl Service for Natsuki {
    async fn bind(mut self, addr: std::net::SocketAddr) -> Result<(), Error> {
        use axum::{response::NoContent, routing::get, Router};
        let router = Router::new().route("/", get(|| async { NoContent }));

        let (axum, serenity) = futures::join!(
            shuttle_axum::AxumService(router).bind(addr),
            self.0.start_autosharded(),
        );
        serenity.map_err(CustomError::new)?;
        axum
    }
}

use dotenv::var;
use serde_json::json;

#[tokio::main]
async fn main() -> anyhow::Result<()> {
    let client = reqwest::Client::new();
    let ping = || async {
        const ENDPOINT: &str = "https://natsuki-oehk.shuttle.app/";
        anyhow::ensure!(client.head(ENDPOINT).send().await?.status().is_success());
        Ok(())
    };
    if let Err(error) = ping().await {
        client
            .post(var("WEBHOOK")?)
            .json(&json!({ "content": error.to_string() }))
            .send()
            .await?;
    }
    Ok(())
}

An o’ish relay is a forcing bid that is natural or has extra strength. Famous examples are Birthright (Kokish Relay, 2♣-2♦-2♥) and Polish Club (1♣), after which I name this treatment. I advocate playing a transfer o’ish relay instead, the relay that either transfers to the next suit or has extra strength. This method renders the negative response nonforcing and allows more descriptive rebids.

I’ve been with my girlfriend for 2+ months and finally found the red and blue mascots for my bridge bidding systems.

• Litten for Litten Polish Club
• Oshawott for Mijumaru Blue Club

Oshawott is my girlfriend’s favorite pokémon. She thinks that Litten is my pokémon since my fursona is an orange cat. These two pokémons fit the color stickers from WBF systems policy and also the Red Oni, Blue Oni trope.

By the way, recently I reached 1800+ Elo on Cuebids. I took a screenshot because I not only was proud of it but also thought it cannot last long.

I’m rewriting Natsuki (3.0) in Rust for several reasons. You can track my progress at this branch.

1. Hosting: Free hosting tend to assume that node.js projects are websites. They put the app to sleep when idle, which effectively takes down a Discord bot. I’m now self-hosting Natsuki, but I’m not a fan of that. Rewriting in another language solves this issue.
2. Economy commands: Shuttle provides free hosting even with 500 MB of database. This means we can make stateful features in the future, such as economy and games.
3. Also please note that I’m considering remove NSFW functions. Discord has been more and more hostile to NSFW features. Making Natsuki SFW can spread her further.

I made a new icon for the Taipei Forcing Club and this site. This icon honors both my hobbies: contract bridge and Japanese mahjong.

I used Inkscape to create the icon. I’m not a graphic designer, but I’m happy with the result. This icon combines lietxia’s 🀙 (1p) mahjong tile and ♣ in Noto Sans TC.

I tested my bidding systems on Cuebids, a web app for pairs to practice bidding. All three accounts using my bidding systems made it to the top 10 this week. The following is the screenshot of the top 10 list when Mijumaru Blue Club (known as Bluepill (Canapé) Club then) just entered the list. My own account and Irene playing only Litten Polish Club were the top two.

We are still on top 5 as of this writing. We will try to stay on top 10 but not to be top 3 at the same time to keep the environment competitive.

My collection of bidding systems is available on GitHub. It contains aforementioned systems and a defensive system. Litten Polish Club is almost complete. Mijumaru Blue Club is still evolving. The defensive system is still in its infancy.

This collection is free software. You can use it for any purpose, including commercial purposes, at your own risk. I would appreciate it if you could share your experience with me.

Inspired by Thomas Andrews’ article on single hand evaluators, I want to check out how good such an evaluator NLTC is. Since LTCs need an established trump fit, we only consider suit offense tricks, i.e. the most tricks a partnership can take in any suit contract.

Thomas built his data with Matt Ginsberg’s (GIB) double dummy library containing 700K+ deals. However, available sources of that library are long gone. To achieve similar statistical power, I would have to solve about 1M deals. Thanks to DDS, the well known double dummy solver in C++, along with modern computer architecture, we can solve 1M deals within one day.

I generated all data in this article with my bridge utility. It took 8 hours to solve 1M deals for only suit contracts. The following is the correlation coefficient matrix of various evaluations.

The plus sign stands for short-suit points in GIB bid descriptions. As BUM-RAP gives fractional points, I made such an adjustment more rigorous.

• S = (void = 3, singleton = 2, doubleton = 1)
• X+ = max(X, S, X + S − 1) for each suit

As for how this adjustment is slightly better than max(X, S) and X + S, there will be a separate article.

ALTC is what Jeff Rubens suggested. Adjust −0.5 losers for each held ace and +0.5 for each guarded queen. NLTC bears this in mind but adjusts for missing aces and queens instead.

Things are different when we add up evaluations in each partnership. LTCs are less additive than HCP+. I think this phenomenon arises from counting values twice. A classic example is that a long suit in one hand and the corresponding doubleton in another are both counted as values a priori.

My favorite defense to strong 1♣ is Psycho Suction. I filled in 2NT and the 1-level as per the useful space principle. This defense is so flexible that it also applies to small 1♣, strong 1♦, and over the forced responder, e.g. (1♣)-(1♦).

Psycho Suction is an extension to the natural defense. It is a superset of the weak twos. The two suiters increase the probabilities of the 2-bids and unanchor them. Psycho Suction establishes a pass-or-correct system where the 2x overcalls are also pass-or-correct. The word “psycho” reflects the risk of playing an undoubled misfit like psychic bids.

Paradox advances

The paradox principle in a pass-or-correct system is to bypass underbids. For example, hearing (1♣)-2♦, we hold

♠ J98
♥ KJ1032
♦ Q98
♣ Q2

Bid 3♦. Besides diamond support, this bid also shows that we can also raise either major. Underbidding 2♥ conveys too little information and takes away too little space.

The paradox lies in that we do not bid our favorite strain. We have to make the cheapest call of the conjectured advances. Resultantly, we usually bid for the worst case.

Comparison with defenses to 1NT

Similarities

The most common subtype of strong 1♣ is a strong notrump. The opener is so strong that we are unlikely to have a game, so our main goal is to compete with partscores. Our cuebid strain is notrump because opponents have shown strength but no suit.

A common way to devise a defense to 1♣ is using our defense to 1NT. Suction is originally a defense to 1NT. Such a defense to 1NT with no anchor suit is banned in the ACBL Basic+ chart.¹ However, artificial defenses to an artifical opening are generally allowed.² Therefore, we can derive a defense to 1♣ from such an exotic defense to 1NT.

Differences

An obvious difference is that we can access 1-level overcalls. Beware of the lowest 2 overcalls as they give out bidding space.

X and 1♦ are better constructive to make bidding space useful to everyone. Natural 1♥ and 1♠ are fine. Try to increase the probability of 2-level overcalls, which take considerable space.

Another difference is that 1NT is limited and descriptive. The opener does not have much to say even if given a second chance to bid. The probability that the opener has a major is also lower. These reasons make major-oriented overcalls effective, e.g. Multi-Landy.

On the other hand, a strong artificial opening is usually unlimited. Forcing overcalls are less effective since they let the opener pass at ease. Thus, a natural defense to 1♣ is stronger than to 1NT. Besides, Inverted Psycho Suction may work for 1NT, but Psycho Suction works better for 1♣.

Discussions

5=4 two suiters

I include some 5=4 two suiters to increase the probabilities of Psycho Suction bids. The rest can be easily expressed with a simple major overcall, where the 4-card suit is lower than the 5-card major.

I believe 5=4 is the sweet spot of two suiters. The original 5-5 is too infrequent to make these overcalls different from weak twos. The 5-4 pattern is as frequent as the single-suited, putting the pass at higher risk. Moreover, 5-4 bids are better guided with an extra step showing equal preference. For example, Landy shows 5-4 in majors, and the 2♦ advance indicates equal preference. Nevertheless, this additional step bears a suit we deny, so it lets opponents come in cheaply.

Strength of X and 1♦

The strength to double is opening values. The double is a two-way call that is either a takeout double or a stolen opening bid with 5+ cards.

The 1♦ overcall is slightly stronger than 1♥ and 1♠ because it gives space yet exhibits no major. I suggest near average strength, i.e. 10+ total points in which there are 8+ HCP. I even recommend this approach to natural 1♣ since 1♦ leaks information without taking space.

Overcalls with 16+ HCP

Congratulations on holding yet another strong club! A comeback after passing the first round definitely reveals 16+ HCP. There are also situations where an initial double is better. To decide the best overcall, we have to investigate their pros and cons.

The pass is better when coming back is easy. The following qualities suggest a pass.

• Single suiter
• 5-card major
• Balanced

The takeout double is made for three suiters. It lets our partner decide the strain. If our partner bids our shortness, we can bid 1NT to provide choices again.

Two suiters fall between these scenarios. First, try to bid 1NT and 2NT since they are forcing. Next, hide a 4-card minor with a pass because introducing the longest suit is often enough. Then, we are left with the following two suiters to double.

• Majors
• 4=5 or more in same-colored suits

When a fit is not found yet, we can easily run to the cheaper suit. This strategy happens to spare 2♣, our rebid to show a regular opener with clubs.