A. Boitmanis & A. Dombrovskis
"Bulletin CSK" 1977
Before the key that will build a battery, the future front piece performs a pair of TRIES, first 1.Ne6? (A) threatening 2.Rd4, but 1...b4! (a) and second 1.Nd3? (B) waiting - but 1...e6! (b) Finally, comes the KEY 1.Rc6! (waiting 1...a/b, 2.A/B). Zugzwang, the focal effect along the 6th horizontal, and the set flight to 'b4' were already important details introduced to enhace the artistic effect (as compared to the prototype launched that same year) - But there was also another feature - linking the refutation of one of the tries to the other try - namelly: If, after 1.Nd3 (B) , comes 1...b4 (a), then 2.Nxb2# (a new mate). This kind of virtual change maybe was not intentional - even if it appears in another #2 by Boitmanis and exactly in a try that takes the flight... Certainlly not - say - programmatic (The required Theme is already difficult enough!) - Even so: Still a plus, a pleasant feature...
V. Sitnikov
"Sahs" 1979
1.c4 A /Ke3 B ; 1... e3 a / Kxc2 b - 1.Bd4! etc Another early example, with a suggestive 1/3 battery along the second horizontal. After the key, we get two different batteries. When the front piece is a Pawn, there's no danger of some random firing! Tries and the actual solution are of the 'Waiting' type (
Brief digression: Usually Zugzwang problems without set-mates will need some very strong justification - being authentic Vladimirovs certainlly is reason enough - as this Theme is possibly the most difficult of this kind! Others count some thousands, 'Vlads' are a few dozens, and the majority are versions of the same matrices - not always improving the contents. ) Relevant in the above example is that we got again a virtual change: After try 1.c4 A, if black answer with defense b 1...Kxc2, a new, purelly virtual 2.Q d2 mate arise. A common characteristic of the examples above, is that one of the tries block the square where the refutation of the other try takes place - hence, they are not suitable for making two of the virtual changed mates ... Could this nice effect be doubled? We can not assert exactly when was this question raised for the first time, but the answer - yes - came just two years after the introduction of the new pattern, and exactly by one of the leading creators in this field . Enjoy this Empire State Building of the 'Vlad's :
Milan Velimirovic
"Schach-Echo" 1979
1-st Prize
SET: 1...Kxc3 2.Qh3 THEMATIC TRIES 1.Sa4? (~) A, 1... ba3! a, if 1... bc3 b then 2.Sc5:#; 1.Sc4:? (~) B , 1... bc3! b, 1... ba3 a 2.Ra3:#; KEY 1.bxc6(en passant)! (~), 1... bc3,ba3 2.Sc4:,Sa4#. ( Besides of a complete & real Vladimirov, he got virtually changed mates - for the first time ! - for A/b AND B/a ; and finally an extra try 1.Qa7? (~), 1... Kc3:!, 1... bc3,bae with a pair of new mates 2.Qa4,Qa3:#) .
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'Black King in the Globe of Death')