まい

1. Origins, structure, and basic meaning

• Structure: After a verb referring to the speaker's action, まい can express a firm resolve not to do it.
• Basic usage: 二度と同じ失敗はするまいと心に決めた。 reports a decision not to repeat the same mistake.

2. Common pitfalls and similar expressions

• Connection and where tense is expressed
  • 悩むまい adds the ending to 悩む, and するまい is also an available form. In するまいと決めた, 決めた places the decision in the past.
• Negative resolve versus negative conjecture
  • 私はもう行くまい can express a resolve not to go, while 彼はもう来るまい can express a conjecture that he will not come. Subject and context distinguish resolve from conjecture.