The Equation of Love and Death (lǐ mǐ de cāi xiǎng 李米的猜想), also called Aishichang (ài shì cháng 爱逝偿) is a 2008 Chinese dramatic film written and directed by Cao Baoping (cáo bǎo píng 曹保平) and starring Zhou Xun (zhōu xùn 周迅). The film is a Chinese Huayi Brothers (huá yì xiōng dì 华谊兄弟) and Hong Kong (xiāng gǎng 香港) co-production. It is Cao's second solo feature after 2006's Trouble Makers (jué duì qíng gǎn 绝对情感). This time, the film concentrates on small potatos: strange woman bus driver, countrified “criminals”, a serious policeman and a mysterious handsome guy. This is not a mysterious movie but a movie reflecting the simple and pure love, distressed and touched, which is just  around our daily life.


How long will you wait for your love? 
A Kunming (kūn míng 昆明) cab driver who spent four years waiting for Fang Wen (fāng wén 方文), who although he disappeared several years ago, continues to write her letters, coming back. During the four years Li Mi (lǐ mǐ 李米) kept thinking of Fang Wen so much that she behaved like an insane person: talking about these unrelated numbers again and again and trying to find out their relation incorrigibly; obsessed with her boyfriend; obsessively reciting the contents of these letters to her rides.This black tragic-comedy-cum-romance is a refreshingly edgy offering from China's still-developing commercial film sector. Anchored by a brilliant performance by major star Zhou Xun, Cao Baoping's second film doesn't let up for a moment.

Plot
Li Mi (lǐ mǐ 李米) is a tough little taxi driver waiting for Fang Wen coming back. She longs for the day pining over her missing boyfriend Fang Wen, and keeps a book of photos inside her cab to show to her passengers, just in case they've seen him. However, country hicks Huo Gui (huǒ guì 火贵) and Shui Tian (shuǐ tiān 水天) secretly steal her photo book when they get into a minor row with Li Mi over change for a cab ride. They end up dropping the book when they happen by a car collision, and one of the drivers happens to be Fang Wen, who's riding with a mysterious female passenger. He picks up the dropped photo book, and after seeing that it's filled with pictures of himself, he chases the two men, only to lose them on the streets.

Clearly up to no good, Huo Gui and Shui Tian end up back in Li Mi's cab, but when she discovers that they're carrying a knife, the situation takes a dangerous turn. Li Mi ends up as their hostage, while Fang Wen ends up haggling with the police over his car accident. Oddly, he's now going by the name Ma Bing (mǎ bīng 马冰).He refused to admit he knew her. Li Mi’s desperate call could not bring Fang Wen back. When the movie reached the ending part we got Fang Wen’s painstaking. He expressed his loyalty to his lover in another way, When Li Mi watched the video which Fang Wen left to her.


Cast
Zhou Xun (zhōu xùn 周迅) as Li Mi, the flim's heroine, the petite Mainland girl has shined in movies as compelling as Hollywood Hong Kong (xiāng gǎng yǒu gè hǎo lái wù 香港有个好莱坞), and as completely weird as Ming Ming (míng míng 明明). Zhou adds to her impressive library of performances with The Equation of Love and Death.
Many people say that the best thing about The Equation of Love and Death is Zhou Xun.
In this movie, Zhou Xun’s performance shocked the audience. Her hoarse voice , the sentimental look in her eyes, and sympathy for the younger poor drug pusher shaped a veritable character in the movie, which is a far cry from her usual romantic heroines. As Li Mi, Zhou runs the gamut from tough to frightened to desperate to elated, her performance carrying nearly every scene, and when she finally smiles from her heart, it's a greater payoff than most films ever achieve.

Zhou Xun owns both the screen and her co-stars with a compelling emotion that, despite its forceful and occasionally showy flourishes, never feels like overacting. Zhou makes Li Mi's volatile obsessive-romantic the centerpiece of the film, and further stakes her claim to being the best film actress in China today.
 

Besides, Deng Chao (dèng chāo 邓超), Zhang Hanyu (zhāng hán yǔ 张涵予) and Wang Baoqiang (wáng bǎo qiǎng 王宝强) also gave us good performances in it. Deng Chao suffers by comparison, though his character is required to be implacable, and Zhang Hanyu turns in strong, wry support as the police officer assigned to Li Mi's case.

The Name of the Movie
The film opens with Li Mi reciting numbers in a seemingly random fashion, and we ultimately learn that they relate to a series of letters sent to her by Fang Wen.
That's the "equation" part. The "love" part comes from Li Mi's ardent refusal to let Fang Wen go. God has little mercy on this poor girl. After four-year bitter waiting, she met him.
The "death" part, Director Cao Baoping provides very little overt exposition, and the audience is sometimes forced to follow the characters blindly as they get involved in one mess after the other. The mystery behind the characters and their actions is revealed gradually.

Reception
Early reviews by western critics suggested that Cao Baoping's sophomore film was a stylish thriller/drama, but that much depended on the power of Zhou Xun's performance as Li Mi. Shelly Kraicer, the Chinese film scholar and curator of the Vancouver International Film Festival's Dragons and Tigers competition noted that while director "Cao Baoping is an expert at orchestrating frenzy," the film ultimately belonged to Zhou Xun. Despite the praise, the film would not go on to win the award (which went to Emily Tang's Perfect Life). Variety critic Derek Elley also wrote in his review that the film was "motored by another saturated performance by the throaty-voiced Zhou."


Other critics saw the film as yet another example of China's growing sophistication with "genre films." The China Film Journal in its final verdict argued that while the film was not "life changing," it was nevertheless a "step in the right direction" and that audiences would not mind "seeing a few more Memento-esque films" coming out of China in the near future.

Awards and Nominations
The film won the Altadis New Directors Award at the 2008 San Sebastian International Film Festival. The Equation of Love and Death premiered in China on September 18, 2008 in Shangha and had its North American premiere at the 2008 Vancouver International Film Festival where it was part of the Dragons and Tigers side competition.