[ъ] = [ǝ], [ь] = [ɪ].

[a] is the symbol for the sound of stressed <a>. The sound of the <a>, <o> in syllables immediately before the stress or word-initially is generally written [ʌ]: <гoрод> [ˈgorǝt̪], <города> [gǝrʌˈd̪а]. And stressed <и> = [i].

Urban 

 

Thank you very much for the explanation, but some questions still exist.

1.  [ъ] = [ǝ], [ь] = [ɪ] . Well, that's what I could expect asking the question, but the point is that I would strongly deny the fact [ъ] and [ь] are equal at least to English [ǝ] and [ɪ] (especially [ɪ] in заяц, лягушка etc seemes to be very far from it's English, especially Am. E. counterpart). May be the IPA just didn't want to go too far in trying to reach accuracy? :)

2. How about unstressed  <и> in syllables immediately before the stress?

Sergei